Timeline of Colorado history: Difference between revisions

Main articles: History of Colorado and Prehistory of Colorado

This is a timeline of the prehistory and history of Colorado and the state's predecessors (e.g., the Colorado Territory, [[Jefferson Territory, etc.).

 2000s   1900s   1800s   1700s   1600s   1500s   Before 1500 

2010s

Year	Date	Event
2013	June 11	Wildfires ignite in Rocky Mountain National Park, the Royal Gorge, and the Black Forest. The Black Forest fire will destroy 486 homes, the most in Colorado history.
	June 5	Lightning ignites the first of several wildfires near Wolf Creek Pass. The West Fork Complex fires will burn over 170 square miles (440 km2) of forest.
	May 1	Civil unions become legal in Colorado for both conventional and same-sex couples, although same-sex marriage remains illegal.
	March 20	Governor John Hickenlooper signs three bills intended to curb firearm violence.
	March 19	Tom Clements, Executive Director of the Colorado Department of Corrections, is assassinated at his home in Monument.
2012	December 10	David J. Wineland of the National Institute of Standards and Technology and the University of Colorado at Boulder and Serge Haroche receive the 2012 Nobel Prize in Physics.
	November 6	Colorado voters approve the legal possession of small quantities of cannabis. Governor John Hickenlooper cautions: ”Federal law still says marijuana is an illegal drug, so don't break out the Cheetos or Goldfish too quickly.“
	September 21	U.S. President Barack Obama issues a proclamation creating Chimney Rock National Monument from 7.4 square miles (19.1 km2) of San Juan National Forest.
	July 30	Missy Franklin of Centennial wins the first of four gold medals in swimming at the Games of the XXX Olympiad in London.
	July 20	A gunman opens fire in a cinema in Aurora killing 12 patrons and wounding 70 more.
	June 25	Sparks ignite the Last Chance Fire on the prairie near Last Chance. This wildfire will burn 69 square miles (178 km2) of grassland and five homes in a few hours.
	June 23	The Waldo Canyon Fire ignites in the foothills northwest of Colorado Springs. This wildfire will force the evacuation of more than 32,000 residents and destroy 347 homes, the most in Colorado to date.
	June 9	A lightning strike ignites the High Park Fire in the mountains west of Fort Collins. This wildfire will destroy 257 homes and grow to become the second most extensive in Colorado recorded history.
	April 28	The History Colorado Center opens in Denver.
2011	November 18	The Clyfford Still Museum opens in Denver.
	October 22	Missy Franklin of Centennial sets a world record time of 2:00.03 in the women's 200 meter backstroke at the Fédération Internationale de Natation (FINA) Swimming World Cup in Berlin.
	September 23	Occupy Denver begins a protest of the growing disparity of wealth and the disproportionate political power of large corporations and extremely wealthy individuals in the United States.
	July 18	Michael Hancock assumes office as the Mayor of the City and County of Denver.
	April 1	CenturyLink, Inc. completes its $24 billion acquisition of the larger Qwest Communications International, Inc. of Denver.
	January 12	Deputy Major Bill Vidal assumes office as the Mayor of the City and County of Denver following the resignation of John Hickenlooper.
	January 11	John Hickenlooper assumes office as the forty-second Governor of the State of Colorado.
2010	November 21	The Colorado Rapids Major League Soccer club defeats FC Dallas 2-1 to win the Major League Soccer Cup championship.
	October 14	Workers uncover a trove of mammoth, mastodon, and other Pleistocene fossils at the Ziegler Reservoir construction site near Snowmass Village. The Denver Museum of Nature and Science will organize the Snowmastodon Project to excavate the site.
	September 6	Fire spreads from a fire pit and ignites the Fourmile Canyon Fire in the mountains west of Boulder. This wildfire will burn 9.7 square miles (25.0 km2) of forest and inflict $217 million of property damage. The fire will destroy 169 homes, more than any previous event in Colorado.
	April 1	2010 United States Census enumerates the population of Colorado, later determined to be 5,029,196, an increase of 16.92% since the 2000 United States Census.

2000s

Year	Date	Event
2009	October 15	The balloon boy hoax discombobulates emergency services in northeastern Colorado.
	February 27	The Rocky Mountain News, the region's oldest and second highest circulation newspaper, publishes its last edition just 55 days before of its sesquicentennial. The Denver Post survives as the city's only major newspaper.
	January 21	Michael Bennet of Denver assumes office as the junior United States Senator from Colorado.
	January 20	Ken Salazar of Denver assumes office as the United States Secretary of the Interior.
	January 3	Mark Udall of Eldorado Springs assumes office as the junior United States Senator from Colorado.
2008	August 28	Barack Obama accepts the nomination of the Democratic National Convention in Denver for President of the United States.
	August 13	Jack Weil, founder and CEO of Rockmount Ranch Wear, dies at his home in Denver at age 107.
	August 4	The extension of Interstate Highway I-270 from I-76 to the intersection of I-25 and US-36 opens to traffic, lengthening I-270 to 7.107 miles (11.438 km).
	February 16	The Bradford Washburn American Mountaineering Museum opens in Golden.
	January 2	EchoStar Communications Corporation of Englewood splits into EchoStar Corporation and Dish Network Corporation.
2007	November 6	The residents of the proposed City of Castle Pines North vote to incorporate, making Castle Pines North the youngest of the 271 active municipalities of the State of Colorado.
	October 15	The Colorado Rockies defeat the Arizona Diamondbacks in four games to win the National League Pennant.
	July 12	The United States Fish and Wildlife Service establishes the Rocky Flats National Wildlife Refuge.
	April 27	The United States National Park Service establishes the Sand Creek Massacre National Historic Site.
	January 9	Bill Ritter assumes office as the forty-first Governor of the State of Colorado.
2006	November 17	The T-REX Project in southeast metropolitan Denver is completed 22 months ahead of schedule.
	November 7	Colorado voters approve an amendment to the Constitution of the State of Colorado banning same-sex marriage.
	October 7	The Denver Art Museum opens its Daniel Libeskind designed Frederic C. Hamilton Building.
	July 28	NORAD's Cheyenne Mountain Realignment redesignated the Cheyenne Mountain Directorate to the Cheyenne Mountain Division which maintains the Cheyenne Mountain nuclear bunker's standby centers.
2005	December 10	Professor John L. Hall of the University of Colorado at Boulder, Theodor W. Hänsch, and Roy J. Glauber receive the 2005 Nobel Prize in Physics.
	June 13	The Cussler Museum opens in Arvada.
	January 1	An act of Congress changes the name of Colorado Canyons National Conservation Area to McInnis Canyons National Conservation Area.
2004	November 2	U.S. President George W. Bush defeats Colorado native John Kerry in the 2004 election for President of the United States.
	September 13	U.S. Secretary of the Interior Gale Norton signs an order elevating the national monument to Great Sand Dunes National Park and Preserve.
2003	November 24	The Northwest Parkway toll road from Broomfield to the intersection of I-25 and E-470 opens to traffic.
	July 18	John Hickenlooper assumes office as the Mayor of the City and County of Denver.
	April 8	The United States Fish and Wildlife Service establishes the Baca National Wildlife Refuge.
	January 3	The last segment of the E-470 toll road opens to traffic.
2002	June 9	The Missionary Ridge Fire starts burning in the mountains north of Durango. The wildfire will burn 110 square miles (285 km2) of forest and 56 homes.
	June 8	A U.S. Forest Service technician starts the Hayman Fire in the mountains of central Colorado. The wildfire will burn 216 square miles (559 km2) of forest, the most in Colorado recorded history.
2001	December 10	Professor Eric Allin Cornell of the University of Colorado at Boulder, Carl Wieman, and Wolfgang Ketterle receive the 2001 Nobel Prize in Physics.
	November 15	The State of Colorado creates the City and County of Broomfield from portions of Boulder, Adams, Jefferson, and Weld counties.
	June	Construction on the T-REX Project in southeast metropolitan Denver begins.
	June 9	The Colorado Avalanche defeat the New Jersey Devils in seven games to win the Stanley Cup.
	January 1	Denver celebrates the beginning of the Third Millennium with fireworks above the 16th Street Mall.
2000	October 24	U.S. President Bill Clinton signs an act of Congress creating the Colorado Canyons National Conservation Area and the Black Ridge Canyons Wilderness.
	October 1	The State of Colorado transfers Buckley Air National Guard Base back to the United States Air Force as Buckley Air Force Base.
	August 21	Xcel Energy Inc. is formed by the merger of New Century Energies, Inc. of Denver into the smaller Northern States Power Company.
	June 30	US West, Inc. of Denver merges into the smaller Qwest Communications International, Inc., also of Denver.
	June 9	U.S. President Bill Clinton signs a proclamation creating Canyons of the Ancients National Monument.
	May 9	The Denver Museum of Natural History changes its name to the Denver Museum of Nature and Science.
	April 7	The American Association of State Highway and Transportation Officials (AASHTO) approves the extension of the Interstate Highway I-270 designation from I-76 northwest to the intersection of I-25 and US-36.
	April 1	2000 United States Census enumerates the population of Colorado, later determined to be 4,301,262, an increase of 30.56% since the 1990 United States Census.

1990s

Year	Date	Event
1999	October 21	U.S. President Bill Clinton signs an act of Congress elevating the national monument to Black Canyon of the Gunnison National Park and creating the Gunnison Gorge National Conservation Area.
	April 20	The Columbine High School massacre: Two high school students open fire on their campus in Jefferson County killing 12 students and a teacher and wounding 24 others before killing themselves.
	January 31	The Denver Broncos defeat the Atlanta Falcons 34 to 19 in Super Bowl XXXIII in Miami, Florida.
	January 17	The Denver Broncos defeat the New York Jets 23 to 10 to win the American Football Conference Championship.
	January 12	Bill Owens assumes office as the fortieth Governor of the State of Colorado.
1998	June 5	The United States Air Force renames Falcon Air Force Base as Schriever Air Force Base.
	January 25	The Denver Broncos defeat the Green Bay Packers 31 to 24 in Super Bowl XXXII in San Diego, California.
	January 11	The wildcard Denver Broncos defeat the Pittsburgh Steelers 24 to 21 to win the American Football Conference Championship.
1997	August 13	The animated television series South Park, set in South Park, debuts.
	August 1	New Century Energies, Inc. of Denver is formed by the merger of Southwestern Public Service Company with the larger Public Service Company of Colorado.
	June 20	The 23rd annual meeting of the G8 convenes in Denver.
	March 12	Federico Peña assumes office as the United States Secretary of Energy.
	January 3	Diana DeGette of Denver succeeds Congresswoman Pat Schroeder in the United States House of Representatives. Congresswoman DeGette still represents Colorado's 1st congressional district.
1996	December 26	The body of JonBenét Ramsey is found in the basement of her home in Boulder.
	September 11	The Southern Pacific Transportation Company merges with the UP Holding Company, Inc. to form the Union Pacific Corporation (the Southern Pacific Railroad becomes part of the Union Pacific Railroad).
	July 22	Amy Van Dyken of Englewood wins the first of her six Olympic gold medals in swimming at the Games of the XXVI Olympiad in Atlanta.
	June 11	The Colorado Avalanche win the Stanley Cup in the 4th game against the Florida Panthers (1st championship for a Colorado major league sports team).
	May 20	The United States Supreme Court rules Colorado Amendment 2 prohibiting establishment of LBGT "minority status" is unconstitutional.
1995	December 28	EchoStar Communications Corporation of Englewood successfully launches its first satellite, EchoStar I.
	June 11	Denver International Airport opens replacing Stapleton International Airport.
	March 25	The Michael Graves designed addition to the central Denver Public Library opens.
1994	December 10	Rashaan Salaam of the University of Colorado Buffaloes football team wins the 1994 Heisman Trophy.
	October 7	The Regional Transportation District begins light rail service in Denver.
	July 6	A blowup of the South Canyon Fire kills 14 wildlands firefighters on Storm King Mountain, near Glenwood Springs.
1993	December 15	Colorado district judge Jeffrey Bayless rules that Colorado Amendment 2 violates the United States Constitution.
	September 15	The interchange of I-76 with I-25 is opened, completing the extended 188.10-mile (302.72 km) length of Interstate Highway I-76 in Colorado. This project completes the Interstate Highway System in Colorado, although improvements and enhancements will continue.
	April	Construction begins to directly connect the intersection of I-270 and I-76 with the intersection of I-25 and US-36.
	January 21	Federico Peña assumes office as the United States Secretary of Transportation.
1992	November 3	Voters approve Colorado Amendment 2 to the state constitution which prohibits "special rights" based upon sexual orientation. Amendment 2 never takes effect due to legal challenges.
		Voters approve Colorado Amendment 1 to the state constitution, also known as the Colorado Taxpayer Bill of Rights (TABOR).
	October 14	Governor Roy Romer dedicates the segment of I-70 through Glenwood Canyon, completing the extended 449.589-mile (723.543 km) length of Interstate Highway I-70 through Colorado.
	October 9	U.S. President George H.W. Bush signs an act of Congress creating the Rocky Mountain Arsenal National Wildlife Refuge.
	May 26	U.S. President George H.W. Bush signs an act of Congress creating the Two Ponds National Wildlife Refuge.
1991	October 15	The Warren Zevon album Mr. Bad Example is released with the song "Things to Do in Denver When You're Dead".
	September 16	U.S. President George H.W. Bush announces the promotion of the Solar Energy Research Institute to the National Renewable Energy Laboratory (NREL), a national laboratory of the United States Department of Energy.
	July 1	Wellington Webb assumes office as the first African-American Mayor of the City and County of Denver.
	June	The first segment of the E-470 toll road opens to traffic.
	January 1	The University of Colorado Buffaloes football team defeat the University of Notre Dame Fighting Irish 10 to 9 to win the Orange Bowl and the Associated Press National Championship Trophy.
1990	November 24	The U.S. Environmental Protection Agency vetoes the Two Forks Dam Project proposed by the Denver Board of Water Commissioners.
	June 23	The Colorado Convention Center opens in Denver.
	April 1	1990 United States Census enumerates the population of Colorado, later determined to be 3,294,394, an increase of 13.99% since the 1980 United States Census.
	January 14	The Denver Broncos defeat the Cleveland Browns 37 to 21 to win the American Football Conference Championship.

1980s

Year	Date	Event
1989	December 10	Professor Thomas Cech of the University of Colorado at Boulder and Sidney Altman receive the 1989 Nobel Prize in Chemistry.
	November 22	The City and County of Denver holds a ground-breaking ceremony for a new airport to replace the aging Stapleton International Airport.
	June 6	The Federal Bureau of Investigation and the Environmental Protection Agency raid the Department of Energy Rocky Flats Plant near Arvada.
1988	November 8	Voters in Adams, Arapahoe, Boulder, Denver, Douglas, and Jefferson counties approved the creation of the Scientific and Cultural Facilities District.
	October 13	The Philip Anschutz controlled Rio Grande Industries, Inc. acquires the Southern Pacific Transportation Company. The Denver and Rio Grande Western Railroad becomes part of the Southern Pacific Railroad.
	June 18	The United States Air Force renames Falcon Air Force Station as Falcon Air Force Base.
	January 17	The Denver Broncos defeat the Cleveland Browns 38 to 33 to win the American Football Conference Championship.
1987	May 8	Colorado U.S. Senator Gary Hart announces the end of his campaign for election as President of the United States.
	April 13	Colorado U.S. Senator Gary Hart announces his campaign for election as President of the United States in 1988.
	April 5	The National Mining Hall of Fame and Museum opens in Leadville.
	January 13	Roy Romer assumes office as the thirty-ninth Governor of the State of Colorado.
	January 11	The Denver Broncos defeat the Cleveland Browns 23 to 20 in overtime to win the American Football Conference Championship. The Drive becomes a part of American football lore.
1985	September 26	The United States Air Force opens the Consolidated Space Operations Center at Falcon Air Force Station near Colorado Springs.
	February 1	Maybell records an ambient air temperature of −61 °F (−51.7 °C), setting the all-time Colorado record low temperature.
1984	November	The Philip Anschutz controlled Anschutz Corporation acquires Rio Grande Industries for $500 million. The new Rio Grande Holdings, Inc. includes the Denver and Rio Grande Western Railroad.
	August 1	A truck carrying six torpedoes for the United States Navy overturns and dumps its potentially explosive load into the intersection of I-25 and I-70 in Denver, the busiest intersection in Colorado known locally as the Mousetrap.
	June 18	Alan Berg is murdered at his home in Denver by members of The Order.
	February 16	Scott Hamilton wins the Olympic gold medal in Men's Figure Skating at the XIV Olympic Winter Games in Sarajevo.
	January 1	US West, Inc. of Denver is formed by the Bell System divestiture. US West is a holding company with three subsidiary regional Bell operators: Mountain States Telephone and Telegraph (dba Mountain Bell), Northwestern Bell Telephone Company (dba Northwestern Bell), and Pacific Northwest Bell Telephone Company (dba Pacific Northwest Bell).
1983	July 1	Federico Peña assumes office as the first Hispanic Mayor of the City and County of Denver.
	May 17	The United States Air Force begins construction of Falcon Air Force Station near Colorado Springs.
1982	December 28	Congressman-elect and former astronaut Jack Swigert of Littleton dies in Washington, D.C. at age 51.
	October 4	The 16th Street Mall in Denver opens.
1981	May 12	The United States and Canada rename the North American Air Defense Command as the North American Aerospace Defense Command.
	January 12	The television series Dynasty, set in metropolitan Denver, debuts.
1980	December 9	Charlie Ergen, Jim DeFranco, and Cantey McAdams form EchoSphere in Littleton.
	April 1	1980 United States Census enumerates the population of Colorado, later determined to be 2,889,964, an increase of 30.93% since the 1970 United States Census.

1970s

Year	Date	Event
1979	December 21	Governor Dick Lamm dedicates the Edwin C. Johnson Bore of the Eisenhower–Johnson Memorial Tunnel completing Interstate Highway 70 under the Continental Divide.
1978	November 10	U.S. President Jimmy Carter signs an act of Congress creating the Continental Divide National Scenic Trail.
	October 9	UNESCO designates Mesa Verde National Park as one of the first 12 World Heritage Sites.
	September 14	The comedy television series Mork & Mindy, set in Boulder, debuts.
	August 1	The United States Olympic Committee moves into its new headquarters at the United States Olympic Training Center in Colorado Springs.
		Federal highway route US-36 is extended westward along Colorado State Highway 66 from Estes Park to Deer Ridge Junction in Rocky Mountain National Park.
	February 26	Boettcher Concert Hall of the Denver Center for the Performing Arts opens in the Denver Performing Arts Complex.
	January 1	The Denver Broncos defeat the Oakland Raiders 20 to 17 to win the American Football Conference Championship.
1977	September 30	Proposed Colorado Interstate Highway I-470 is withdrawn from the Interstate Highway System.
	July 28	Governor Dick Lamm requests that the proposed 26.3-mile (42.3 km) Colorado Interstate Highway I-470 be withdrawn from the Interstate Highway System.
	July 5	United States Department of Energy opens the Solar Energy Research Institute (SERI) in Golden.
	June	The United States Olympic Training Center at the former Ent Air Force Base in Colorado Springs opens to athletes.
1976	October 1	The former Ent Air Force Base closes in Colorado Springs.
	August 1	A somber State of Colorado observes its centennial as it assesses the damage from the Big Thompson Flood the previous evening.
	July 31	A flash flood in Big Thompson Canyon kills 143 people just hours before the Colorado State Centennial.
	July 4	Colorado celebrates the United States Bicentennial.
	May 21	The final segment of I-225 is opened in Denver, completing the entire 11.959-mile (19.246 km) length of Interstate Highway I-225.
	March 1	The United States Air Force renames Peterson Field in Colorado Springs as Peterson Air Force Base.
1975	August 18	Construction of the second bore of the Eisenhower Tunnel begins.
	April 1	The United States Air Force renames Ent Air Force Base as the Ent Annex of Peterson Air Force Base.
	January 14	Dick Lamm assumes office as the thirty-eighth Governor of the State of Colorado.
1974	December 21	The first Telluride Film Festival begins.
	August 1	Interstate highway I-80S is redesignated I-76. Over 500 route markers will be replaced in Colorado over the next two years.
		The United States Army renames Fitzsimons Army Hospital in Aurora as Fitzsimons Army Medical Center.
		Chogyam Trungpa establishes the Naropa Institute in Boulder.
1973	September 8	Rebecca Ann King of Denver is crowned Miss America.
	July 16	Lieutenant Governor John Vanderhoof assumes office as the thirty-seventh Governor of the State of Colorado upon the resignation of Governor John Love to serve as Director of the United States Office of Energy Policy.
	June 21	The United States Supreme Court orders the complete desegregation of the Denver Public Schools in Keyes v. School District No. 1.
	May 17	The United States Atomic Energy Commission detonates three underground nuclear explosions in Colorado. Project Rio Blanco used the three nearly simultaneous blasts, each equivalent to 33,000 tonnes of TNT, to determine if nuclear explosions could be used to extract natural gas from sandstone deposits.
	March 8	Governor John Love dedicates the first bore of the Eisenhower Tunnel taking Interstate Highway 70 under the Continental Divide of the Americas, the highest point on the Interstate Highway System.
	January 3	Pat Schroeder of Denver takes her seat in the United States House of Representatives as Colorado's first woman delegate to the U.S. Congress. Congresswoman Schroeder will represent Colorado's 1st congressional district for 24 years.
1972	November 15	Denver withdraws its offer to host the 1976 Winter Olympics, the first and only host city to reject an awarded Olympic Games.
	November 7	Colorado voters reject a $5 million bond issue to fund the 1976 Winter Olympics.
	September 10	Frank Shorter of Boulder wins the Men's Marathon at the Games of the XX Olympiad in Munich.
1971	October 3	The United States Department of Transportation opens the High Speed Ground Test Center east of Pueblo.
	May 19	The Denver Art Museum opens its Gio Ponti designed North Tower.
1970	October 23	The final segment of I-270 is opened, completing the 5.2-mile (8.4 km) Interstate Highway I-270.
	April 13	An oxygen tank manufactured in Boulder exploded on the Apollo 13 space flight to the moon. The three-man crew, including Command Module Pilot Jack Swigert of Denver, managed to fly safely back to Earth four days later.
	April 1	1970 United States Census enumerates the population of Colorado, later determined to be 2,207,259, an increase of 25.85% since the 1960 United States Census.

1960s

Year	Date	Event
1969	October	The John Denver debut album Rhymes & Reasons is released.
	September 21	The final 21-mile (34 km) segment of Interstate Highway I-25 south of Walsenburg opens to traffic, completing the entire 305.040-mile (490.914 km) length of I-25 in Colorado.
	September 10	Project Rulison detonates a Garland County 40KT underground nuclear explosion (1st in Colorado) to test natural gas extraction from shale gas deposits (cf., Rifle, Colorado, detonation in 1972).
	August 20	U.S. President Richard Nixon signs an act of Congress creating Florissant Fossil Beds National Monument.
		The City of Wheat Ridge in eastern Jefferson County incorporates.
	July 1	The State of Colorado creates the Regional Transportation District to promote public transportation in the Denver metropolitan area.
	June 24	The City of Lakewood in eastern Jefferson County incorporates.
	May 12	The International Olympic Committee selects Denver to host the XII Olympic Winter Games in 1976.
	May 11	A plutonium fire in Building 776/777 of the Atomic Energy Commission Rocky Flats Plant contaminated the plant near Arvada in the most expensive U.S. industrial accident to date.
1968	December 13	US Secretary of Transportation announces the plan to expand the Interstate Highway System, including the 5.6-mile (9.0 km) extension of Interstate Highway I-80S from I-25 to I-70.
	March 15	Construction begins on the first bore of the Straight Creek Tunnel designed to route Interstate Highway I-70 under the Continental Divide.
	February 10	Peggy Fleming wins the Olympic gold medal in Women's Figure Skating at the X Olympic Winter Games in Grenoble.
1967	September 17	The Denver-Boulder Turnpike becomes the first public toll road in the United States to pay for itself and becomes a freeway. The turnpike becomes a portion of the westward extension of federal highway route US-36 from Denver to Estes Park.
	September 5	The United States Fish and Wildlife Service establishes the Arapaho National Wildlife Refuge.
1966	October 19	Blue Mesa Dam on the Gunnison River in Gunnison County is completed.
	January 1	Air Force Systems Command turned the Cheyenne Mountain Combat Operations Center over to NORAD.
1965	December 12	Interstate Highway I-270 construction begins in Denver.
	July 25	The United States Fish and Wildlife Service establishes the Browns Park National Wildlife Refuge.
	June 16	A flash flood on the South Platte River kills 28 people and inflicts over $500 million in damage.
	March 26	The last Titan I ICBM of the former Lowry Bombing and Gunnery Range was taken off alert status (all Titan 1s were in storage by April 18).
1964	July 3	The Robert Ward opera The Lady from Colorado premieres at the Central City Opera.
	June 11	The musical film The Unsinkable Molly Brown premieres in Denver.
	May	Construction of Interstate Highway I-225 begins in Aurora.
		Stapleton Airfield in Denver is renamed Stapleton International Airport.
1963	December	Dillon Dam on the Blue River in Summit County is completed.
	September	Eminent nuclear physicist Edward Condon joins the faculty of the University of Colorado.
	July 25	The United States Fish and Wildlife Service establishes the Alamosa National Wildlife Refuge.
	March 1	Dr. Thomas Starzl performs the world's first liver transplant at the University of Colorado Hospital in Denver.
	January 8	John Love assumes office as the thirty-sixth Governor of the State of Colorado.
1962	May 24	Astronaut Scott Carpenter from Boulder becomes the fourth person to orbit the Earth.
	April 24	The first of a series of minor earthquakes emanating from a region below the United States Army Rocky Mountain Arsenal near Denver is recorded. The earthquakes are later tied to the injection of toxic fluids into a hazardous waste disposal well at the chemical weapons plant.
	April 24	U.S. Deputy Attorney General Byron White is sworn in as a Justice of the United States Supreme Court. White will serve on the court for 31 years.
1961	July 20	Tunneling began for the NORAD Cheyenne Mountain nuclear bunker (the bunker plan for the Denver Air Defense Sector had been cancelled in 1959, and the SAC bunker near Cripple Creek planned for 1965 was cancelled in 1963.)
	April 26	The United States Air Force activates the Titan I ICBM 725th Strategic Missile Squadron stationed east of Lowry Air Force Base.
1960	November 3	The Meredith Willson musical The Unsinkable Molly Brown opens at the Winter Garden Theatre.
	June 23	U.S. President Dwight Eisenhower signs an order creating Comanche National Grassland and Pawnee National Grassland.
	June 3	U.S. President Dwight Eisenhower signs a proclamation creating Bent's Old Fort National Historic Site.
		Construction of Interstate Highway I-70 begins near Idaho Springs.
	April 18	The United States Air Force transfers Buckley Air Force Base to the Colorado Air National Guard as Buckley Air National Guard Base.
	April 1	1960 United States Census enumerates the population of Colorado, later determined to be 1,753,947, an increase of 32.36% since the 1950 United States Census.
	February 9	Brewer Adolph Coors III is murdered in a foiled kidnap attempt near his home in Bear Creek Canyon west of Denver.

1950s

Year	Date	Event
1959	June 3	The first class of the United States Air Force Academy graduates.
	September 1	Lowry Missile Site No. 1 construction began southeast of Denver for a Titan I launch complex--construction of the supporting Martin Missile Test Site 1 at Waterton Canyon had begun in April (alert status ended in March 26, 1965).
	January 22	The Adolf Coors Company of Golden introduces the aluminum beer can.
1958	December 10	Edward Lawrie Tatum from Boulder, George Wells Beadle, and Joshua Lederberg receive the 1958 Nobel Prize in Physiology or Medicine.
	August	Construction of Interstate Highway I-80S begins in northeastern Colorado.
	May 12	The United States and Canada establish the North American Air Defense Command (NORAD) headquartered at Ent Air Force Base.
1957	October 18	United States Secretary of Commerce Sinclair Weeks announces that 2,102 miles (3,383 km) of highway routes will be added to the Interstate Highway System. Included is the 547-mile (880 km) westward extension of Interstate Highway I-70 from I-25 in Denver to I-15 near Cove Fort, Utah.
	September 11	A plutonium fire in Building 71 of the Atomic Energy Commission Rocky Flats Plant contaminates the plant and releases radioactive plutonium into the air near Denver.
	September 7	Marilyn Van Derbur of Denver is crowned Miss America.
	January 8	Steve McNichols assumes office as the thirty-fifth Governor of the State of Colorado.
1956	November 10	Professor George Gamow (Георгий Антонович Гамов) of the University of Colorado is awarded the 1956 UNESCO Kalinga Prize.
	October 15	The Denver Public Library dedicates the new central library at the Denver Civic Center
	July 7	The Douglas Moore opera The Ballad of Baby Doe premieres at the Central City Opera.
1955	November	Construction begins on the Monument Valley Freeway in Colorado Springs. The Monument Valley Freeway will be incorporated into Interstate Highway I-25.
	September 24	U.S. President Dwight Eisenhower suffers an acute myocardial infarction in Denver. The President is treated at Fitzsimons Army Hospital in Aurora for several weeks.
	September 11	Sharon Kay Ritchie of Colorado Women's College is crowned Miss America.
	July 11	The first class of 306 cadets of the United States Air Force Academy are sworn in at Lowry Air Force Base in Denver.
	January 11	Ed Johnson assumes office again as the thirty-fourth Governor of the State of Colorado.
	January 3	Gordon L. Allott takes his seat in the United States Senate. He will serve as a U.S. Senator from Colorado for 18 years.
1954	August 27	The United States Army upgrades Camp Carson to Fort Carson.
	June 24	The United States Air Force selects an area north of Colorado Springs as the site for the United States Air Force Academy.
1952	September 3	The United States Fish and Wildlife Service establishes the Monte Vista National Wildlife Refuge.
	July 18	Denver television station KFEL-TV (analog channel 2) begins the first television broadcasts in Colorado.
	January 19	The Denver-Boulder Turnpike opens to traffic.
1951	July 10	Construction of the United States Atomic Energy Commission Rocky Flats Plant begins 15 miles (24 km) northwest of Denver.
	January 9	Dan Thornton assumes office as the thirty-third Governor of the State of Colorado.
	January 8	The United States Air Force opens Ent Air Force Base in Colorado Springs.
	January 3	Byron G. Rogers of Denver takes his seat in the United States House of Representatives. Congressman Rogers will represent Colorado's 1st congressional district for 20 years.
1950	April 15	Lieutenant Governor Walter Johnson assumes office as the thirty-second Governor of the State of Colorado upon the resignation of Governor Bill Knous to serve as a federal judge.
	April 1	1950 United States Census enumerates the population of Colorado, later determined to be 1,325,089, an increase of 17.96% since the 1940 United States Census.
	February 13	The FIS Alpine World Ski Championships 1950 open at the Ajax Mountain Ski Resort at Aspen, the first World Championships held outside Europe.

1940s

Year	Date	Event
1949		Construction begins on the Pueblo Freeway in Pueblo. The Pueblo Freeway will be incorporated into Interstate Highway I-25.
	January 3	Wayne N. Aspinall of Palisade takes his seat in the United States House of Representatives. Congressman Aspinall will represent Colorado's 4th congressional district for 24 years.
1948	August 15	The Colorado Museum of Natural History changes its name to the Denver Museum of Natural History.
	August	Construction begins on the Valley Highway in Denver. The Valley Highway will be incorporated into Interstate Highway I-25.
	June 24	The United States Air Force renames Lowry Field in Denver as Lowry Air Force Base.
1947		Denver FM radio station KLZ-FM begins commercial broadcasting at 106.7 MHz in the new U.S. FM broadcast band.
	January 14	William Lee Knous assumes office as the thirty-first Governor of the State of Colorado.
1946	December 14	The Ajax Mountain Ski Area opens at Aspen with the world's longest chairlift.
	May	The Army Air Service Command transfers Fort Logan to the Veterans Administration.
1945	September 10	Mike the Headless Chicken survives an assassination attempt but loses his head near Fruita.
	September 2	World War II ends as the Empire of Japan formally surrenders.
	May 8	The war in Europe ends as the Greater German Empire formally surrenders.
1944	August 25	Denver Municipal Airport is renamed Stapleton Airfield.
1943	December 17	U.S. President Franklin Roosevelt signs the Magnuson Act repealing the Chinese Exclusion Act of 1882. Naturalization of persons of Asian descent is permitted for the first time. Chinese immigration is severely restricted.
		The Colorado Springs Tent Camp was established at the edge of Colorado Springs and west of Peterson Field. ("Ent Air Force Base" in 1949, "Ent Annex" in 1975).
	January 12	John Charles Vivian assumes office as the thirtieth Governor of the State of Colorado.
1942	August 27	The United States Army renames Colorado Springs Army Air Base as Peterson Army Air Base.
	August 27	The Granada War Relocation Center (Camp Amache) opens for Japanese-American internees.
	July	Governor Ralph Carr opposes the internment of Japanese-Americans despite the war with Japan.
	June 30	The United States Army begins construction of the Rocky Mountain Arsenal near Denver to produce chemical weapons for the war effort.
	April 28	The United States Army opens the Colorado Springs Army Air Base at the Colorado Springs Municipal Airport.
	April	The United States Army begins construction of Camp Hale near Tennessee Pass.
	April	The United States Army begins construction of Buckley Field east of Aurora.
	February	The United States Army begins construction of the Pueblo Ordnance Depot.
	January 6	The United States Army announces the selection of Colorado Springs as the site of a major Army base, designated Camp Carson a few weeks later.
1941	December 11	The Greater German Empire and the Kingdom of Italy declare war on the United States.
	December 8	The Empire of Japan declares war on the United States following its attack on Pearl Harbor. The United States declares war on the Empire of Japan and enters World War II.
	June 15	Rotary International celebrates the Grand Opening of Red Rocks Amphitheatre with 10,000 in attendance during their annual convention. An "informal dedication" was held the week before.
	January 3	William S. Hill of Fort Collins and John Chenoweth of Trinidad take their seats in the United States House of Representatives. Congressman Hill will represent Colorado's 2nd congressional district for 18 years and Congressman Chenoweth will represent Colorado's 3rd congressional district for 22 years.
1940	April 1	1940 United States Census enumerates the population of Colorado, later determined to be 1,123,296, an increase of 8.45% since the 1930 United States Census.

1930s

Year	Date	Event
1939	January 10	Ralph Carr assumes office as the twenty-ninth Governor of the State of Colorado.
1938	December 2	U.S. President Franklin Roosevelt signs an order creating the Colorado State Forest.
1937	October 4	The Works Progress Administration (WPA) begins construction of Lowry Field in Denver for the United States Army Air Corps.
	September 6	The Will Rogers Shrine of the Sun is dedicated along the 1925 Cheyenne Mountain Highway that leads to the Cheyenne Mountain Lodge.
	February 7	A donated rope tow begins operation at Berthoud Pass, creating Colorado's first public tow-assisted alpine skiing. Unfortunately, two skiers are killed in an avalanche the same day.
	January 12	Teller Ammons assumes office as the twenty-eighth Governor of the State of Colorado.
	January 3	Ed Johnson takes his seat in the United States Senate. He will serve as a U.S. Senator from Colorado for 18 years.
	January 1	Lieutenant Governor Ray Herbert Talbot assumes office as the twenty-seventh Governor of the State of Colorado upon the resignation of Governor Ed Johnson to serve in the United States Senate.
1936	May 9	Members of Civilian Conservation Corps (CCC) Company 1848 at Morrison Camp SP-13-C in Red Rocks Park cease work on all other projects in preparation for the construction of Red Rocks Amphitheatre, Colorado's premier outdoor concert venue and one of the biggest projects of its kind undertaken by the CCC.
1935	March 8	Elizabeth Bonduel McCourt "Baby Doe" Tabor is found frozen to death in her cabin near the Matchless Mine in Lake County.
1934	May 17	The Dotsero Cutoff between the Denver and Salt Lake Railway and the mainline of the Denver and Rio Grande Western Railroad is completed, cutting the rail distance between Denver and Salt Lake City by 173 miles (278 km). The 38.1 mile (61.3 km) cutoff runs from Dotsero to Orestod (Dotsero spelled backwards). The cutoff is now part of the Union Pacific line between Denver and Salt Lake City and one of Amtrak's most popular routes.
1933	March 2	Outgoing U.S. President Herbert Hoover signs a proclamation creating Black Canyon of the Gunnison National Monument.
	January 10	Ed Johnson assumes office as the twenty-sixth Governor of the State of Colorado.
1932	March 28	U.S. President Herbert Hoover signs an order changing the name of Colorado National Forest to Roosevelt National Forest.
	March 17	U.S. President Herbert Hoover signs an act of Congress creating Great Sand Dunes National Monument.
1930	April 1	1930 United States Census enumerates the population of Colorado, later determined to be 1,035,791, an increase of 10.23% since the 1920 United States Census.

1920s

Year	Date	Event
1929	November	The City of Cañon City completes the Royal Gorge Bridge over the Arkansas River.
	October 17	Denver Municipal Airport opens.
1928	February 26	The 6.2 mile (10.0 km) long Moffat Tunnel under the Continental Divide of the Americas opens as the world's longest railway tunnel.
1927	January 11	Billy Adams assumes office as the twenty-fifth Governor of the State of Colorado.
1926		Spencer Penrose establishes his Cheyenne Mountain Zoo near the BROADMOOR.
1925	November 25	The silent film The Phantom of the Opera is released starring Lon Chaney of Colorado Springs.
	June	Adams State Normal School opens in Alamosa.
	January 13	Clarence Morley assumes office as the twenty-fourth Governor of the State of Colorado.
1924	June 2	U.S. President Calvin Coolidge signs an Act of Congress extending United States citizenship and suffrage to all American Indians born in the United States.
1923	March 2	U.S. President Warren G. Harding signs a proclamation creating Hovenweep National Monument.
	January 9	William Ellery Sweet assumes office as the twenty-third Governor of the State of Colorado.
1922	March 10	Denver radio station W9ZAF receives a commercial license as KLZ (AM 560 kHz), the first commercial radio station in Colorado.
1921	July 21	The 66th United States Congress changes the name of the Grand River to the Colorado River so that the state's namesake actually flows through the state. The names of Grand County, Grand Lake, Grand Mesa, Grand Valley, and Grand Junction remain unchanged.
	June 3	Flash floods on the Arkansas River and Fountain Creek kill 1500 people and inflict over $20 million of damage around Pueblo.
1920	December 5	The silent film The Mark of Zorro is released starring Douglas Fairbanks of Denver.
	July	The United States Army renames Army Hospital 21 in Aurora as Fitzsimons Army Hospital.
	April 1	1920 United States Census enumerates the population of Colorado, later determined to be 939,629, an increase of 17.60% since the 1910 United States Census.

1910s

Year	Date	Event
1919	December 19	U.S. President Woodrow Wilson signs a proclamation creating Yucca House National Monument.
	July 4	Jack Dempsey of Manassa defeats Jess Willard in a bout at Toledo, Ohio for the World Heavyweight Boxing Championship.
1918	November 11	An armistice ends the fighting of the Great War.
		The Denver Art Association becomes the Denver Art Museum.
	June 29	The BROADMOOR resort opens near Colorado Springs.
	May 14	Denver Mayor Robert W. Speer dies at home in Denver at age 62.
		The United States Army begins construction of Army Hospital 21 in Aurora.
1917	April 6	The United States declares war on the German Empire and enters the Great War.
	April 2	U.S. President Woodrow Wilson urges a joint session of the United States Congress to declare war on the German Empire.
	January 10	William Frederick "Buffalo Bill" Cody dies in Denver at age 70.
	January 9	Julius Caldeen Gunter assumes office as the twenty-first Governor of the State of Colorado.
1916	July 1	U.S. Army Lieutenant Dwight D. Eisenhower marries Mary "Mamie" Geneva Doud in Denver.
1915	October 4	U.S. President Woodrow Wilson signs a proclamation creating Dinosaur National Monument.
	March 4	Charles B. Timberlake of Sterling takes his seat in the United States House of Representatives. Congressman Timberlake will represent Colorado's 2nd congressional district for 18 years.
	January 26	U.S. President Woodrow Wilson signs an act of Congress creating Rocky Mountain National Park
	January 12	George Alfred Carlson assumes office as the twentieth Governor of the State of Colorado.
1914	April 20	The Colorado National Guard attacks a tent colony of striking colliers and their families encamped at Ludlow, Colorado, killing 19 men, 2 women, and 11 children. Over ten days, the Ludlow Massacre and its aftermath leave over 100 dead. President Woodrow Wilson calls out federal troops to pacify the conflict.
1913	December 1	Denver's greatest snowfall ever begins. Denver receives a five-day accumulation of 45.7 inches (1161 mm), while Georgetown gets 86 inches (2184 mm).
	March 8	The State of Colorado creates Alamosa County from portions of Costilla and Conejos counties.
	January 14	Elias M. Ammons assumes office as the nineteenth Governor of the State of Colorado.
1912	April 26	The Colorado Mountain Club is founded in Denver.
	April 15	The RMS Titanic strikes an iceberg and sinks. Margaret Brown of Denver is hailed as a heroine by survivors.
1911	November	The Daniels & Fisher Tower opens in Denver.
	July 17	The Mountain States Telephone and Telegraph Company is formed in Denver.
	May 29	The State of Colorado creates Crowley County from a portion of Otero County.
	May 24	U.S. President William Howard Taft signs a proclamation creating Colorado National Monument.
	February 27	The State of Colorado creates Moffat County from a portion of Routt County.
1910	July 1	U.S. President William Howard Taft signs an order creating Colorado National Forest.
	April 1	1910 United States Census enumerates the population of Colorado, later determined to be 799,024, an increase of 48.05% since the 1900 United States Census.
	February 15	The Denver Public Library dedicates its new library building.

1900s

Year	Date	Event
1909	July 17	The Shoshone Hydroelectric Generating Station begins operation on the Grand River in Glenwood Canyon. The plant begins transmitting electric power to the Denver area over the 153.4-mile (247 km) three-phase 90,000 volt Shoshone Transmission Line.
	May 5	The State of Colorado creates Jackson County from the western portion of Larimer County.
	March 4	Edward T. Taylor takes his seat in the United States House of Representatives. Congressman Taylor will represent Colorado in the U.S. House for more than 32 years.
	January 19	The Denver, Northwestern and Pacific Railway reaches Steamboat Springs.
	January 12	John F. Shafroth assumes office as the eighteenth Governor of the State of Colorado.
1908	July 10	The Democratic National Convention meeting in Denver nominates William Jennings Bryan for President of the United States
	July 1	U.S. President Theodore Roosevelt signs an order creating Arapaho National Forest.
		The Colorado Museum of Natural History opens its new building in Denver City Park.
1907	March 4	The Town of Fletcher changes its name to the Town of Aurora.
	January 8	Henry Augustus Buchtel assumes office as the seventeenth Governor of the State of Colorado.
1906	June 29	U.S. President Theodore Roosevelt signs an act of Congress creating Mesa Verde National Park.
	August 1	The Argentine Central Railway reaches the 13,587-foot (4141 m) summit of Mount McClellan.
	February 24	U.S. President Theodore Roosevelt signs an order creating the Fruita Forest Reserve.
	January 29	The first Western Livestock Show opens in Denver. The show will become the National Western Stock Show, Rodeo and Horse Show.
	January 25	U.S. President Theodore Roosevelt signs an order creating the La Sal Forest Reserve.
1905	August 25	U.S. President Theodore Roosevelt signs an order creating the Holy Cross Forest Reserve.
	June 14	U.S. President Theodore Roosevelt signs an order creating the Uncompahgre Forest Reserve.
	June 13	U.S. President Theodore Roosevelt signs orders creating the Cochetopa Forest Reserve and the Montezuma Forest Reserve.
	June 12	U.S. President Theodore Roosevelt signs orders creating the Park Range Forest Reserve, the San Isabel Forest Reserve, and the Wet Mountains Forest Reserve.
	June 5	U.S. President Theodore Roosevelt signs an order creating the San Juan Forest Reserve.
	May 12	U.S. President Theodore Roosevelt signs orders creating the Gunnison Forest Reserve, the Leadville Forest Reserve, and the Pike's Peak Forest Reserve.
	May 9	The first water flows over the spillway of the new Cheesman Dam on the South Platte River in Jefferson and Douglas counties. The dam is the world's tallest at 221 feet (67.3 m).
	March 17	This becomes Colorado's day with three governors as Alva Adams, James Hamilton Peabody, and Jesse Fuller McDonald sequentially serve as the Governor of the State of Colorado.
	January 10	Alva Adams assumes office again as the fourteenth Governor of the State of Colorado.
1904	June 1	Robert W. Speer assumes office as the Mayor of the City and County of Denver.
	May 21	U.S. President Theodore Roosevelt signs an order creating the White River Forest Reserve.
1903	May 5	The Town of Fletcher incorporates. The town will change its name to Aurora four years later, and eventually grow to become the third most populous municipality in Colorado.
	April 11	The State of Colorado reverts the name of South Arapahoe County back to Arapahoe County.
	January 13	James Hamilton Peabody assumes office as the thirteenth Governor of the State of Colorado.
1902	November 15	After a prolonged court battle, the State of Colorado splits Arapahoe County into three new counties: the City and County of Denver, South Arapahoe County, and Adams County.
	July 18	The Denver, Northwestern and Pacific Railway incorporates in Denver. The company plans to build a direct rail line from Denver to Salt Lake City via a lengthy tunnel under the Continental Divide of the Americas.
	May 22	U.S. President Theodore Roosevelt signs an order creating the Medicine Bow Forest Reserve.
1901	January 8	James Bradley Orman assumes office as the twelfth Governor of the State of Colorado.
	January 1	Harry Heye Tammen and Frederick Gilmer Bonfils rename the Denver Evening Post as The Denver Post.
1900	December 6	The Colorado Museum of Natural History in Breckenridge is incorporated.
	April 1	1900 United States Census enumerates the population of Colorado, later determined to be 539,700, an increase of 30.60% since the 1890 United States Census.

1890s

Year	Date	Event
1899	June 1	Nikola Tesla (Никола Тесла) begins research on the wireless transmission of power at his new laboratory in Colorado Springs.
	March 23	The State of Colorado creates Teller County from portions of El Paso and Fremont counties.
	January 10	Charles Spalding Thomas assumes office as the eleventh Governor of the State of Colorado.
1898	August 12	The United States and the Kingdom of Spain sign a Protocol of Peace ending fighting in the Spanish American War.
	April 25	The United States declares war on the Kingdom of Spain.
	April 23	The Kingdom of Spain declares war on the United States.
	April 19	U.S. Senator Henry M. Teller of Colorado offers the Teller Amendment to a Joint Resolution of Congress to ensure that the United States will not establish permanent control over Cuba after any conflict with Spain.
1897	January 12	Alva Adams assumes office again as the tenth Governor of the State of Colorado.
1896	November 7	The Denver Zoo opens.
1895	November 3	Tammen and Bonfils rename the Evening Post as the Denver Evening Post.
	October 28	Harry Heye Tammen and Frederick Gilmer Bonfils purchase the Evening Post of Denver for $12,500.
	January 8	Albert Washington McIntire assumes office as the ninth Governor of the State of Colorado.
1894	July 1	The Florence and Cripple Creek Railroad reaches Cripple Creek.
	March 14	The Denver City Police and the Arapahoe County Deputy Sheriffs barricade Denver City Hall to prevent the Colorado State Infantry from seizing the building in the City Hall War of 1894.
1893	November 7	Colorado becomes the first U.S. state to give women the vote by popular referendum.
	November 1	U.S. President Grover Cleveland signs the Repeal of the Sherman Silver Purchase Act. The repeal fails to halt the Panic of 1893 and plunges Colorado into a massive depression.
	July 22	Katherine Lee Bates visits the summit of Pikes Peak and writes the poem America the Beautiful.
	March 27	The State of Colorado creates Mineral County from portions of Hinsdale, Rio Grande, and Saguache counties.
	January 10	Davis Hanson Waite assumes office as the eighth Governor of the State of Colorado.
1892	December 24	U.S. President Benjamin Harrison signs an order creating the Battlement Mesa Forest Reserve.
	August	Political supporters of Grover Cleveland found the Evening Post in Denver with $50,000.
1891	October 16	The Denver and Rio Grande Railroad reaches Creede.
	October 16	U.S. President Benjamin Harrison signs an act of Congress creating the White River Plateau Timberland Reserve, the second U.S. national forest reserve.
	July 1	The Broadmoor Casino opens near Colorado Springs.
	January 13	John Long Routt assumes office as the seventh Governor of the State of Colorado.
1890	October 22	The Manitou and Pike's Peak Railway completes the rack and pinion line to the 14,115-foot (4,302 m) summit of Pikes Peak.
	October 20	Rancher Robert Miller Womack discovers a rich gold lode along Cripple Creek near Pikes Peak. The Cripple Creek Mining District will produce more than 730 tonnes of gold, the most of any Rocky Mountain district.
	July 14	U.S. President Benjamin Harrison signs the Sherman Silver Purchase Act.
	July 4	Governor Job Cooper lays the cornerstone of the new Colorado State Capitol on Brown's Bluff in Denver.
	April 1	1890 United States Census enumerates the population of Colorado, later determined to be 413,249, an increase of 112.66% since the 1880 United States Census.

1880s

Year	Date	Event
1889	June 24	The Denver and Rio Grande Railroad reaches Lake City.
	June	The City of Denver establishes the Denver Public Library.
	April 16	The State of Colorado creates Baca County from a portion of Las Animas County, and Montezuma County from a portion of La Plata County.
	April 11	The State of Colorado creates Kiowa, Kit Carson, Lincoln, and Prowers counties from portions of Bent and Elbert counties.
	April 9	The State of Colorado creates Sedgwick County from a portion of Logan County.
	March 27	The State of Colorado creates Phillips County from a portion of Logan County.
	March 25	The State of Colorado creates Cheyenne County from portions of Elbert and Bent counties, Otero County from a portion of Bent County, and Rio Blanco County from a portion of Garfield County.
	March 15	The State of Colorado creates Yuma County from a portion of Washington County.
	February 19	The State of Colorado creates Morgan County from a portion of Weld County.
	January 8	Job Adams Cooper assumes office as the sixth Governor of the State of Colorado.
1888	December 18	Richard Wetherill and Charlie Mason find the Cliff Palace on Mesa Verde.
	July 11	Bennett records an ambient air temperature of 118 °F (47.8 °C), setting the all-time state record high temperature.
	April 9	The Denver, Texas and Fort Worth Railroad begins service between Denver and Fort Worth.
	January 1	The Missouri Pacific Railroad begins service between Pueblo, Kansas City, and Saint Louis.
1887	November 5	The Atchison, Topeka and Santa Fe Railroad reaches Denver.
	October 31	The United States Army establishes Fort Logan southwest of Denver.
	October 28	The Denver and Rio Grande Railroad reaches Aspen.
	October 6	The Denver and Rio Grande Railroad reaches Glenwood Springs via Glenwood Canyon.
	September 3	The Colorado Midland Railroad begins service between Colorado City and Leadville via Buena Vista and Hagerman Tunnel under the Continental Divide of the Americas.
	February 25	The State of Colorado creates Logan County from a portion of Weld County.
	February 9	The State of Colorado creates Washington County from a portion of Weld County.
	January 11	Alva Adams assumes office as the fifth Governor of the State of Colorado.
1886	June 19	The Town of Colorado Springs incorporates. Colorado Springs is the seat of El Paso County.
1885	November 15	The Town of Silverton incorporates. Silverton is the seat of San Juan County.
		The Town of Pueblo incorporates. Pueblo is the seat of Pueblo County.
		The Town of Greeley incorporates. Greeley is the seat of Weld County.
	April 14	The State of Colorado creates Archuleta County from a portion of Conejos County.
	January 13	Benjamin Harrison Eaton assumes office as the fourth Governor of the State of Colorado.
1884	April	The Georgetown, Breckenridge and Leadville Railway reaches SilverPlume via the Georgetown Loop.
1883	March 2	The State of Colorado creates San Miguel County from a portion of San Juan County, and reverts the name of Uncompaghre County back to Ouray County.
	February 27	The State of Colorado renames Ouray County as Uncompaghre County.
	February 14	The State of Colorado creates Mesa County from a portion of Gunnison County.
	February 12	The Town of Fort Collins incorporates. Fort Collins is the seat of Larimer County.
	February 11	The State of Colorado creates Eagle County from a portion of Summit County, and Delta and Montrose counties from portions of Gunnison County.
	February 10	The State of Colorado creates Garfield County from a portion of Summit County.
	January 9	James Benton Grant assumes office as the third Governor of the State of Colorado.
1882	December 19	The Denver and Rio Grande Railroad reaches the Colorado-Utah Territory border west of Grand Junction.
	November 21	The Denver and Rio Grande Railroad reaches Grand Junction.
	November 7	An earthquake now estimated to be 6.6 on the Richter scale strikes the northern Front Range. The quake is the most intense in Colorado recorded history.
	September 8	The Denver and Rio Grande Railroad reaches Montrose.
	September 6	The Denver, South Park and Pacific Railroad reaches Gunnison via the Alpine Tunnel under the Continental Divide of the Americas.
	July 8	The Denver and Rio Grande Railroad reaches Silverton.
	June 26	The Chicago, Burlington and Quincy Railroad reaches Denver.
	May 7	The Denver and New Orleans Railroad begins service between Denver and Pueblo.
	May 6	U.S. President Chester A. Arthur signs the Chinese Exclusion Act banning Chinese immigration to the United States and denying citizenship to all persons of Chinese ancestry.
	April 18	Henry M. Teller of Colorado is confirmed as the 15th United States Secretary of the Interior.
	April 13	Oscar Wilde visits Leadville and later writes, "They afterwards took me to a dancing saloon where I saw the only rational method of art criticism I have ever come across. Over the piano was printed a notice : — PLEASE DO NOT SHOOT THE PIANIST. HE IS DOING HIS BEST."
1881	November 24	The Denver and Rio Grande Railroad reaches Crested Butte.
	November 8	The City of Denver is made the permanent capital of the State of Colorado by state referendum.
	August 8	The Denver and Rio Grande Railroad reaches Gunnison.
	July 27	The Denver and Rio Grande Railroad reaches Durango.
	June 1	Denver Union Station opens.
	March 4	The State of Colorado creates Dolores County from a portion of Ouray County.
	February 23	The State of Colorado creates Pitkin County from a portion of Gunnison County.
	February 21	The Colorado Electric Company incorporates in Denver.
1880	July 22	The Denver and Rio Grande Railroad reaches Leadville. The first passenger train to Leadville carries former President Ulysses Grant, the man who brought Colorado statehood.
	June 1	The Denver and Rio Grande Railroad reaches the Colorado-New Mexico Territory border south of Antonito.
	April 1	1880 United States Census enumerates the population of the State of Colorado, later determined to be 194,327, an increase of 387% since the 1870 United States Census.
	March 27	The Denver and Rio Grande Railway reaches a legal accommodation with the Atchison, Topeka and Santa Fe Railroad known as the Treaty of Boston.
	March 3	The Denver, South Park and Pacific Railroad reaches Buena Vista.

1870s

Year	Date	Event
1879	September 1	Colorado Agricultural College opens to students. The land-grant college is renamed Colorado State College of Agriculture and Mechanic Arts in 1935, and renamed Colorado State University in 1957.
	July	The Colorado Historical Society is founded in Denver.
	May 7	The first passenger train passes through the Royal Gorge.
	April 21	The United States Supreme Court rules in the Royal Gorge War between the Denver and Rio Grande Railway and the Atchison, Topeka, and Santa Fe Railroad.
	February 24	The Denver Telephone Dispatch Company opens for business.
	February 10	The State of Colorado abolishes Carbonate County after two days and splits its territory between a new Chaffee County and a renamed Lake County.
	February 8	The State of Colorado renames Lake County as Carbonate County.
	January 14	Frederick Walker Pitkin assumes office as the second Governor of the State of Colorado.
1878	December 7	The Atchison, Topeka and Santa Fe Railroad reaches Raton Pass on the Santa Fe Trail, blocking the Denver and Rio Grande Railway's route to Santa Fe.
	June 26	The Denver and Rio Grande Railway reaches Alamosa.
	April 19	The Royal Gorge War begins as a construction crew of the Atchison, Topeka and Santa Fe Railroad blocks a crew of the Denver and Rio Grande Railway from building into the Royal Gorge.
	May 22	The Colorado Central Railroad reaches Central City.
	January 1	David May opens The Great Western Auction House and Clothing Store in Leadville. The company will become a component of Macy's, Inc.
1877	September 16	The Solid Muldoon is uncovered on Muldoon Hill near Beulah.
	September	David May, Jacob Holcombe, and Thomas Dean open a dry goods store in Leadville.
	August 13	The Colorado Central Railroad reaches Georgetown.
	March 9	The State of Colorado creates Custer County from a portion of Fremont County, and Gunnison County from a portion of Lake County.
	January 29	The State of Colorado creates Routt County from a portion of Grand County.
	January 18	The State of Colorado creates Ouray County from portions of Hinsdale and Lake counties.
1876	November 1	The General Assembly of the State of Colorado convenes for the first time.
	October 3	The State of Colorado holds its first election. Territorial Governor John Long Routt is elected the first Governor of the State of Colorado. Henry M. Teller and Jerome B. Chaffee are elected to the United States Senate. James B. Belford is elected to the United States House of Representatives.
	August 1	U.S. President Ulysses S. Grant signs the presidential declaration admitting the State of Colorado to the Union. Denver remains the capital.
	July 4	The Colorado Territory observes the United States Centennial.
	July 1	Voters of the Colorado Territory approve the proposed Colorado State Constitution.
	June 25	The Battle of the Little Bighorn kills hundreds in the Montana Territory. In the Territory of Colorado, the startling news of the battle sobers celebration of the United States Centennial and anticipation of statehood.
	March 14	The Territory of Colorado establishes the University of Colorado at Boulder.
		The Colorado Constitutional Convention meeting in Denver adopts a constitution for the proposed State of Colorado for submission to voters.
	February 29	The Atchison, Topeka and Santa Fe Railroad reaches Pueblo.
	January 31	The Colorado General Assembly creates San Juan County from a portion of Lake County.
1875	October 25	The Colorado Constitutional Convention convenes in Denver to write a constitution for the proposed State of Colorado.
	October 5	Ulysses S. Grant becomes the first U.S. President to travel beyond the 100th meridian west and visit the Colorado Territory. The President is met by enthusiastic crowds.
	March 29	U.S. President Ulysses S. Grant appoints John Long Routt as the eighth (and last) Governor of the Territory of Colorado.
	March 3	U.S. President Ulysses S. Grant signs the Colorado Enabling Act for statehood.
		U.S. President Ulysses S. Grant signs the Page Act limiting the immigration of Asians into the United States.
1874	July 6	The Denver and Rio Grande Railway reaches Cañon City.
	June 19	U.S. President Ulysses S. Grant appoints Edward M. McCook as the seventh Governor of the Territory of Colorado.
	February 10	The Colorado General Assembly creates Hinsdale, La Plata, and Rio Grande counties from portions of Conejos, Costilla, and Lake counties.
	February 9	The Territory of Colorado purchases the Territorial School of Mines in Golden from the Episcopal Church for $5,000.
		The Territory of Colorado abolishes Platte County after organizers fail to secure voter approval. The territory of the county is returned to Weld County.
	February 6	The Territory of Colorado abolishes Greenwood County and divides its territory between Elbert County and Bent County.
	February 3	The Colorado General Assembly creates Elbert County from a portion of Douglas County, and Grand County from a portion of Summit County.
1873	September 17	The Denver and Boulder Valley Railroad reaches Boulder.
	June 16	The Town of Walsenburg incorporates. Walsenburg is the seat of Huerfano County.
	April 4	U.S. President Ulysses S. Grant appoints Samuel Hitt Elbert as the sixth Governor of the Territory of Colorado.
1872	December 15	The Colorado Central Railroad reaches Black Hawk.
	November 15	The Town of Fairplay incorporates. Fairplay is the seat of Park County.
	October 9	The first Southern Colorado Agricultural and Industrial Exposition is held in Pueblo. The exposition will become the Colorado State Fair.
	October 2	The Denver, South Park and Pacific Railroad incorporates in Denver. The company plans to build a narrow gauge railway from Denver through South Park to the Gunnison River and west through the Utah Territory.
	June 15	The Denver and Rio Grande Railway reaches Pueblo.
	April 3	The Town of Cañon City incorporates. Cañon City (also spelled Canyon City and Canon City) is the seat of Fremont County.
	February 11	The Colorado General Assembly creates Platte County from the eastern portion of Weld County.
1871	November 4	The City of Boulder incorporates. Boulder City is the seat of Boulder County.
	October 27	The Denver and Rio Grande Railway is completed from Denver to the new town of Colorado Springs located five miles (8 km) east of Colorado City.
	January 2	The City of Golden incorporates. Golden City is the former territorial capital and the seat of Jefferson County.
1870	October 27	The Denver and Rio Grande Railway incorporates in Denver. The company plans to build a narrow gauge railway from Denver south to Santa Fe, New Mexico Territory; El Paso, Texas; and on to Mexico City. The railway would intersect all the transcontinental routes built south of Denver.
	September 22	The Colorado Central Railroad reaches Golden.
	August 15	The Kansas Pacific Railroad is completed to Denver. The railroad connects Denver to Kansas City, Missouri and the east, the first all-rail transcontinental route.
	June 22	The Denver Pacific Railroad is completed to Denver. The railroad connects Denver to the Union Pacific mainline at Cheyenne in the Wyoming Territory.
	May 2	Episcopal Bishop George Maxwell Randall begins construction of the Territorial School of Mines at Golden City.
	April 1	1870 United States Census enumerates the population of the Territory of Colorado, later determined to be 39,864, an increase of 16% since the 1860 United States Census.
	February 11	The Colorado General Assembly creates Bent and Greenwood counties from former Cheyenne and Arapaho tribal land and portions of Huerfano County

1860s

Year	Date	Event
1869	December 14	Nathan Meeker, agricultural editor of the New York Tribune, appeals to readers of high moral character to help him build a utopian farming community between the Cache La Poudre River and the South Platte River in the Territory of Colorado. Meeker will name the community Greeley in honor of his publisher, Horace Greeley.
	November 13	The Denver Gas Company incorporates in Denver City.
	July 4	Deer Trail hosts the world's first organized rodeo.
	June 14	U.S. President Ulysses S. Grant appoints Edward M. McCook as the fifth Governor of the Territory of Colorado.
	March 4	Commanding General of the United States Army Ulysses S. Grant assumes office as the 18th President of the United States.
1868	May 23	Brigadier General Kit Carson dies at new Fort Lyon at age 58.
	January 10	The Colorado General Assembly incorporates the Town of Georgetown. Georgetown is the seat of Clear Creek County and still operates under this 1868 Territorial Charter.
1867	December 9	The Colorado General Assembly votes to move the territorial capital from Golden City to Denver City, the seat of Arapahoe County.
	November 18	The Union Pacific Railroad arrives at Julesburg, Colorado. Only nine miles (14 km) of the Union Pacific mainline are built through the northeast corner of the Territory of Colorado.
	April 24	U.S. President Andrew Johnson appoints Alexander Cameron Hunt as the fourth Governor of the Territory of Colorado.
	January 31	U.S. President Andrew Johnson signs an Act of Congress extending voting rights to all negro males in the organized incorporated territories of the United States. Citizenship and suffrage are not extended to American Indians or Asian Americans. No women may vote.
1866	December 29	The Colorado General Assembly creates Saguache County from portions of Lake and Costilla counties.
	March 6	Brigadier General Kit Carson takes command of Fort Garland in the San Luis Valley in an effort to make peace with the Ute Nation.
	February 9	The Colorado General Assembly creates Las Animas County from a portion of Huerfano County.
1865	October 17	U.S. President Andrew Johnson appoints Alexander Cummings of Pennsylvania as the third Governor of the Territory of Colorado.
	September	The (white male) voters of the Territory defeat a referendum for universal male suffrage by a vote of 476 to 4,192, denying the vote to Negros, Indians, and Asians, as well as women.
	July 18	U.S. President Andrew Johnson demands that John Evans resign as the Governor of the Territory of Colorado following an investigation of the Sand Creek Massacre.
	April 15	U.S. Vice President Andrew Johnson assumes office as the 17th President of the United States upon the assassination of Abraham Lincoln.
1864	November 29	Colonel (and the Reverend) John Chivington orders his troops to attack Cheyenne and Arapaho encamped in peace along Sand Creek (now Big Sandy Creek) in the horrific Sand Creek Massacre.
	October 22	The United States Army moves Camp Collins downstream to the present site of Fort Collins.
	May 13	A flash flood on Cherry Creek sweeps away most low-lying structures of Denver City and separates many residents from their local saloons and brothels.
	March 3	Governor John Evans and the Reverend John Chivington found Colorado Seminary in Denver City. The seminary will close in 1868, but reopen in 1880 as the University of Denver.
1862	August 14	The Colorado General Assembly votes to move the territorial capital from Colorado City to Golden City, the seat of Jefferson County.
	July 22	The United States Army establishes Camp Collins near Colona.
	July 7	The second session of the Colorado General Assembly convenes in Colorado City.
	April 6	Alferd Packer arrives at the Los Pinos Indian Agency in the Cochetopa Hills with no trace of his five companions. Upon questioning, Packer admits that he ate his companions.
	March 28	Colorado and New Mexico volunteers repulse invading Texas cavalry at the Battle of Glorieta Pass.
	March 26	U.S. President Abraham Lincoln appoints John Evans of Illinois as the second Governor of the Territory of Colorado.
	March 10	An expeditionary force of Texas cavalry captures Santa Fe for the Confederacy.
	February 9	Alferd Packer and five companions leave the camp of Ouray on the Uncompahgre River bound for the Cochetopa Hills.
1861	December 3	The Colorado General Assembly reincorporates the City of Denver, Auraria, and Highland as the City of Denver, still known as Denver City. While Denver City is no longer the territorial capital, it remains the seat of Arapahoe County.
	November 7	The Colorado General Assembly renames Guadalupe County as Conejos County after only six days.
	November 5	The Colorado General Assembly votes to move the territorial capital from Denver City to Colorado City, the seat of El Paso County.
	November 1	The Colorado General Assembly creates 17 counties: Arapahoe, Boulder, Clear Creek, Costilla, Douglas, El Paso, Fremont, Gilpin, Guadalupe, Huerfano, Jefferson, Lake, Larimer, Park, Pueblo, Summit, and Weld County.
	September 9	The first session of the Colorado General Assembly convenes in Denver City. The General Assembly will reenact many laws of the Provisional Government of the Territory of Jefferson.
	June 6	After meeting with Colorado Territorial Governor William Gilpin, Jefferson Territorial Governor Robert Williamson Steele issues a proclamation declaring the Territory of Jefferson officially disbanded.
	May 29	Colorado Territorial Governor William Gilpin arrives in Denver City.
	April 12	South Carolina artillery opens fire on Fort Sumter in the first engagement of the American Civil War.
	March 25	U.S. President Abraham Lincoln appoints William Gilpin of Missouri as the first Governor of the Territory of Colorado.
	March 4	Abraham Lincoln assumes office as the 16th President of the United States.
	February 28	Outgoing U.S. President James Buchanan signs the organic act creating the free Territory of Colorado. The new Colorado Territory is 41% less extensive than the Jefferson Territory, including all but the eastern 3 miles (5 km), the northern 138 miles (222 km), and the western 50 miles (80 km) of the extralegal territory. The new territory is named for the Colorado River which drains, but does not flow through, the western portion of the territory. The boundaries of the present State of Colorado remain unchanged from the boundaries initially defined and later surveyed for the Territory of Colorado.
	January 29	U.S. President James Buchanan signs the act of admission admitting the eastern portion of the Kansas Territory to the Union as the free State of Kansas. The westernmost 3 miles (5 km) of the new state overlap with land claimed by the Jefferson Territory. The western portion of the former Kansas Territory, and its goldfields, becomes unorganized territory of the United States, although the Provisional Government of the Territory of Jefferson continues to act as the de facto government.
1860	November 13	The Jefferson Territorial Legislature moves from Denver City to Golden City, the seat of Jefferson County.
	November 7	Abraham Lincoln is elected President of the United States. Seven slave states will subsequently secede from the Union.
	August 7	Governor Robert Steele issues a proclamation proposing a merger of the Jefferson Territory with the Kansas Territory. The Kansas Territory, embroiled in a bitter dispute between free-state and slave-state factions, rejects the proposal.
	April 1	The 1860 United States Census attempts to enumerate the population of the goldfields. The count of 34,277 may have been substantially less than the actual population since many residents were in the backcountry prospecting for gold.
	February 1	The Territory of New Mexico creates Mora County from parts of Taos County and San Miguel County. The new county extends into the southern portion of the Jefferson Territory and present day Colorado.
	January 23	The second session of the Jefferson Territorial Legislature convenes in Denver City, the seat of Arrappahoe County.
	January 1	At the behest of the Jefferson Territorial Legislature, Samuel Beall writes a memorial to the Congress of the United States requesting federal approval for the newly formed Territory of Jefferson. The Congress, embroiled in the national debate over slavery, does not respond.

1850s

Year	Date	Event
1859	December 3	The Jefferson Territory grants a charter to the consolidated City of Denver, Auraria, and Highland, commonly known as Denver City. Denver City is the capital of the Jefferson Territory and the seat of Arrappahoe County.
	November 28	The Jefferson Territory creates 12 counties: Arrappahoe, Cheyenne, El Paso, Fountain, Heele, Jackson, Jefferson, Mountain, North, Park, St. Vrain, and Saratoga County.
	November 7	The first session of the Jefferson Territorial Legislature convenes in Denver City.
	October 24	Voters of the goldfields approve the Provisional Government of the Territory of Jefferson by a vote of 1,852 to 280 and elect Robert Williamson Steele the first (and only) Governor of the Territory of Jefferson.
	September 24	Voters of the goldfields reject a proposal to create a Provisional State of Jefferson.
	June 16	Golden City is established 13 miles (21 km) west of Denver City in northwestern Kansas Territory.
	May 6	Prospector John H. Gregory discovers the first hard rock gold in the region, a rich gold-bearing vein (the Gregory Lode) in a mountain ravine (Gregory Gulch) 28 miles (45 km) west of Denver City in northwestern Kansas Territory. Gregory Gulch soon becomes the center of gold mining activity in the region.
	April 23	William Byers publishes the first edition of the Rocky Mountain News, the region's first newspaper, at Denver City (last published February 27, 2009, in its sesquicentennial year as the region's oldest newspaper.)
	February 10	The Boulder City Town Company is established to develop the Boulder City goldcamp in southwestern Nebraska Territory.
	February 7	After news of gold strikes in Arapahoe County, Kansas Territory arrives, the Territory of Kansas splits Arapahoe County into the six counties of Arapahoe, Broderick, El Paso, Fremont, Montana, and Oro, and creates the new Peketon County farther east and south. The counties are never organized.
1858	November 22	William Larimer establishes the rival townsite of Denver City across Cherry Creek from Auraria.
	November 1	Green Russell establishes the townsite of Auraria near the Cherry Creek Diggings in Arapahoe County, Kansas Territory.
		Placer gold deposits are found at several locations near the South Platte River in northwestern Kansas Territory.
	September	News of the discovery of gold along the South Platte River reaches Omaha, precipitating the Pike's Peak Gold Rush.
	August	The townsite of Montana City is established one mile (1.6 km) north of the Little Dry Creek Diggings in Arapahoe County, Kansas Territory.
	July	Prospector Green Russell discovers gold near the mouth of Little Dry Creek in Arapahoe County, Kansas Territory.
		Antoine Janis establishes the town of Colona on the Cache la Poudre River in western Nebraska Territory.
		The U.S. Army builds Fort Garland in the San Luis Valley to replace Fort Massachusetts six miles to the north.
1857	summer	Mexican-American prospectors from the Territory of New Mexico dig for gold along the South Platte River below the mouth of Little Dry Creek in Arapahoe County, Kansas Territory.
1856	January 5	The Territory of Utah creates Beaver County from a part of Iron County which extends into present day western Colorado.
1855	August 25	The Territory of Kansas creates Arapahoe County in the extreme western portion of the territory in what is now Colorado. Despite several attempts, the county is never organized.
1854	May 30	U.S. President Franklin Pierce signs the Kansas–Nebraska Act creating the Territory of Kansas and the Territory of Nebraska. The new territories include present day eastern Colorado.
1852	June 22	The U.S. Army establishes Fort Massachusetts in the San Luis Valley of northern New Mexico Territory, the first U.S. Army fort in what is now Colorado.
	March 3	The new Territory of Utah creates ten counties, including Great Salt Lake, Green River, Iron, Sanpete, Utah, and Washington counties which extend into present day western Colorado.
	January 9	The new Territory of New Mexico creates nine original counties, including Taos County which extends into present day southern Colorado.
1851	April 9	Mexican-American settlers from the area of Taos establish the village of San Luis de la Culebra in the San Luis Valley of northern New Mexico Territory, the first permanent European-American settlement in what is now Colorado.
1850	September 9	U.S. President Millard Fillmore signs the organic acts creating the Territory of New Mexico and the Territory of Utah as part of the Compromise of 1850. The new territories include present day southern and western Colorado.
	June 22	Prospector Lewis Ralston pans one-quarter ounce (6 g) of gold near the mouth of Ralston Creek. Unimpressed, the party continues on to the California goldfields.

1840s

Year	Date	Event
1849	August 21	Proprietor William Bent destroys Bent's Fort.
1848	December 22	A private expedition led by John C. Frémont seeking a route for a proposed railroad from St. Louis to San Francisco along the 38th parallel north becomes hopelessly mired in the snow covered La Garita Mountains. Ten men and 160 mules die in the reckless winter venture.
	February 2	The United States and Mexico sign the Treaty of Guadalupe Hidalgo ending the Mexican–American War. Mexico relinquishes Texas and its northern territories to the United States, reducing its territorial extent by 55% and its population by 20%. The treaty brings the entire area of the future State of Colorado under the control of the United States.
	January 24	James W. Marshall discovers gold at Sutter's Mill near Coloma, California, precipitating the California Gold Rush.
1846	August 18	Troops under the command of Brigadier General Stephen W. Kearny seize the territorial capital of Santa Fe for the United States with little resistance.
	July 31	Brigadier General Stephen W. Kearny stages his troops at Bent's Fort in preparation for an invasion of the Mexican territory of Santa Fe de Nuevo México.
	May 13	The United States declares war on Mexico.
	April 25	The first skirmish of the Mexican–American War.
1845	December 29	The United States admits the Republic of Texas to the Union as the slave State of Texas. The boundaries of the state remain undefined. Mexico maintains that Texas is still its territory and that it will fight to regain Texas. The United States maintains that its border with Mexico is now the Rio Grande (Rio Bravo del Norte).
1842	June 10	U.S. Army Lieutenant John C. Frémont commences a two-year survey of the routes west from the Platte River with guide Kit Carson and cartographer Charles Preuss. The survey report with maps drawn by Preuss become the guides to the Oregon Trail, California Trail, Mormon Trail, and South Platte Trail.

1830s

Year	Date	Event
1838	October 6	Fort Jackson is closed. Trading goods are moved to Fort George and Fort Jackson is destroyed.
1837	spring	Frontier traders Peter Sarpy and Henry Fraeb establish Fort Jackson on the South Platte River.
	spring	Frontier trader Lancaster Lupton establishes Fort Lancaster on the South Platte River 12 miles upstream from the mouth of Saint Vrain Creek.
	spring	Frontier trader Ceran de Hault de Lassus de Saint Vrain establishes Fort Saint Vrain (also known as Fort George) at the confluence of the South Platte River with Saint Vrain Creek.
1836	May 14	Texians force captured General Antonio de Padua María Severino López de Santa Anna y Pérez de Lebrón to sign the Treaties of Velasco recognizing the independence of the Republic of Texas. Mexico never ratifies these treaties.
	May 2	Texians (immigrants from the United States living in the Mexican state of Coahuila y Tejas) declare the independence of the Republic of Texas from Mexico.
1835	October 2	The Texian Revolt begins with the Battle of Gonzales.
	spring	Frontier traders Louis Vasquez and Andrew Sublette establish Fort Vasquez on the South Platte River.
1833	spring	Frontier trader William Bent establishes Bent's Fort on the north bank of the Arkansas River on the Santa Fe Trail.
1831		Mexico ratifies the Adams–Onís Treaty with the United States.

1820s

Year	Date	Event
1821	September 1	William Bucknell and a party of frontier traders leave New Franklin, Missouri bound for Santa Fe by way of the upper Arkansas and Purgatoire rivers. The Bucknell route will become the Santa Fe Trail.
	August 24	The Kingdom of Spain finally recognizes the independence of Mexico with the signing of the Treaty of Córdoba.
	February 22	The Adams–Onís Treaty takes effect defining the new border between the territory of Spain and the United States.
1820	July 14	Botanist Edwin James and two other members of Major Stephen H. Long’s expedition make the first recorded ascent of Pikes Peak. Long names the mountain James Peak, but the name Pike's Peak persists.

1810s

Year	Date	Event
1819		Spanish Governor Facundo Melgares orders the construction of a military fort near Sangre de Cristo Pass to block a possible invasion of Santa Fe de Nuevo México from the United States.
	February 22	The United States and Spain sign the Adams–Onís Treaty. The United States relinquinshes its claim to land west of the 100th meridian west of Greenwich and south and west of the Arkansas River and south of the 42nd parallel north. Spain relinquishes Florida.
1810	August 1	Mexican priest Miguel Hidalgo y Costilla proclaims the independence of Mexico from the Kingdom of Spain in the village of Dolores.

1800s

Year	Date	Event
1807	February 26	Spanish cavalrymen arrest a U.S. Army reconnaissance expedition led by Captain Zebulon Pike in the San Luis Valley. The reconnaissance party is taken to Chihuahua, and then expelled from Mexico.
1806	November 27	Zebulon Pike abandons his attempt to climb the great summit of the Mexican Mountains now known as Pikes Peak.
	November 15	A U.S. Army reconnaissance expedition led by Captain Zebulon Pike first sights the great summit of the Mexican Mountains that will later bear his name.
1803	December 20	France turns its colony of La Louisiane over to the United States. The United States and Spain disagree over the western boundary of the territory. The United States maintains that Louisiana includes the Mississippi River and its entire western watershed. Spain maintains that Louisiana includes the Mississippi River and just the land a short distance west of the river. The area in dispute includes all land in the present State of Colorado east of the Continental Divide and the Sangre de Cristo Divide.
	April 30	The United States and the French Republic sign the Louisiana Purchase Treaty.
1800	October 1	Under pressure from Napoléon Bonaparte, the Kingdom of Spain transfers the colony of Luisiana back to the French Republic with the secret Third Treaty of San Ildefonso.

1770s

Year	Date	Event
1776		A Spanish The Dominguez-Escalante Expedition from August 10 - September 10 travels in western Colorado (e.g., Mesa Verde while maping the Colorado Plateau and the surrounding mountains for a future trade route.

1760s

Year	Date	Event
1765	July	Governor Tomás Vélez Cachupin of Santa Fe de Nuevo México dispatches an expedition led by Juan Maria Antonio Rivera to explore the San Juan Mountains and the Colorado Plateau.
1762	November 13	Fearing the loss of its American territories in the Seven Years War, the Kingdom of France transfers its colony of La Louisiane to the Kingdom of Spain with the secret Treaty of Fontainebleau.

1730s

Year	Date	Event
1739	July 5	French Canadian voyageurs Pierre Antoine and Paul Mallet travel up the Arkansas River to the Purgatoire River and encounter an Arikara who agrees to guide them to Santa Fe. Their journey to Santa Fe marks the first contact between France and Spain in the Rocky Mountain region.

1600s

Year	Date	Event
1692	September 14	Diego de Vargas Zapata y Luján Ponce de León y Contreras completes the reconquest of the Spanish colony of Santa Fe de Nuevo Méjico to end the Pueblo Revolt.
1682	April 9	René-Robert Cavelier, Sieur de La Salle, claims the Mississippi River and its watershed for the Kingdom of France and names the region La Louisiane in honor of King Louis XIV. La Salle has no idea that the river has the fourth most extensive watershed on Earth, some 1,236,388 square miles (3,202,230 km2) in area. The Mississippi Basin includes lands inhabited by hundreds of thousands of native peoples and previously claimed by England, France, and Spain.
1680	August 10	The shaman Popé of the Ohkay Owingeh pueblo leads the Pueblo Revolt against the Spanish rulers of Santa Fe de Nuevo Méjico. The Spanish settlers flee down the Rio Grande to El Paso del Norte.

1500s

Year	Date	Event
1598	July 12	Don Juan de Oñate Salazar establishes the Spanish colony of Santa Fe de Nuevo Méjico at the village of San Juan de los Caballeros adjacent to the Ohkay Owingeh Pueblo.
1541		A Spanish military expedition led by Francisco Vásquez de Coronado, Governor of Nueva Galicia, searches the Great Plains for Quivira.
before 1525		Jicarilla Apache migrate to present southern Colorado and northern New Mexico from Alaska and Northwestern Canada by 1525, and possibly as early as 1300.

Before 1500

Year	Event
1276–1299 CE	A prolonged drought on the Colorado Plateau forces many Ancestral Puebloans to migrate southeast into the Rio Grande Valley.
about 1100 CE	Ancestral Puebloans begin construction of cliff houses on Mesa Verde.
about 550 CE	Ancestral Puebloans move onto Mesa Verde.
8910-8640 BCE	Paleoamericans of the Folsom culture camp at the Lindenmeier Site (in what is today Larimer County.)
about 14,000 BCE	Ice-age Paleoamericans begin using the ice-free corridor east of the Rocky Mountains to migrate throughout the Americas.

 2000s   1900s   1800s   1700s   1600s   1500s   Before 1500 

See also

• Colorado
• Outline of Colorado
• Index of Colorado-related articles
• History of Colorado
  • Prehistory of Colorado
    • History of Mesa Verde
• List of timelines
• Native Americans in the United States
  • Ancestral Puebloans
  • Arapaho Nation
  • Cheyenne Nation
  • Comanche Nation
  • Jicarilla Apache Nation
  • Shoshone Nation
  • Ute Nation
• United States
  • State of Colorado
  • State of Deseret
  • Territory of Colorado
  • Territory of Jefferson
  • Territory of Kansas
  • Territory of Louisiana
  • Territory of Missouri
  • Territory of Nebraska
  • Territory of New Mexico
  • Territory of Utah
• Viceroyalty of New Spain
  • Mexico
    • Santa Fe de Nuevo México