List of counties in Pennsylvania

List of Pennsylvania counties:

1. Adams County, formed in 1800 from parts of York County.
2. Allegheny County, formed in 1788 from parts of Washington and Westmoreland Counties.
3. Armstrong County, formed in 1800 from parts of Allegheny, Lycoming, and Westmoreland Counties.
4. Beaver County, formed in 1800 from parts of Allegheny and Washington Counties.
5. Bedford County, formed in 1771 from parts of Cumberland County.
6. Berks County, formed in 1752 from parts of Chester, Lancaster and Philadelphia Counties.
7. Blair County, formed in 1846 from parts of Huntingdon and Bedford Counties.
8. Bradford County, formed in 1810 from parts of Luzerne and Lycoming Counties; originally called Ontario County, renamed as Bradford County in 1812.
9. Bucks County, one of the original counties at the formation of Pennsyvania in 1682.
10. Butler County, formed in 1800 from parts of Allegheny County.
11. Cambria County, formed in 1804 from parts of Somerset and Huntingdon Counties.
12. Cameron County, formed in 1860 from parts of Clinton, Elk, McKean, and Potter Counties.
13. Carbon County, formed in 1843 from parts of Monroe and Northampton Counties.
14. Centre County, formed in 1800 from parts of Lycoming, Mifflin, Northumberland, and Huntingdon Counties.
15. Chester County, one of the original counties at the formation of Pennsylvania in 1682.
16. Clarion County, formed in 1839 from parts of Venango and Armstrong Counties.
17. Clearfield County, formed in 1804 from parts of Lycoming and Huntingdon Counties; Clearfield functioned as a part of Centre County for judiciary purposes until 1822.
18. Clinton County, formed in 1839 from parts of Lycoming and Centre Counties.
19. Columbia County, formed in 1813 from parts of Northumberland and Luzerne Counties.
20. Crawford County, formed in 1800 from parts of Allegheny County.
21. Cumberland County. formed in 1750 from parts of Lancaster County.
22. Dauphin County, formed in 1785 from parts of Lancaster County.
23. Delaware County, formed in 1789 from parts of Chester County.
24. Elk County, formed 1843 from parts of Jefferson, McKean, and Clearfield Counties.
25. Erie County, formed in 1800 from parts of Allegheny County; attached to Crawford County until 1803.
26. Fayette County, formed in 1783 from parts of Westmoreland County.
27. Forest County, formed in 1848 from parts of Jefferson County; attached to Jefferson County until 1857.
28. Franklin County, formed in 1784 from parts of Cumberland County.
29. Fulton County, formed in 1850 from parts of Bedford County.
30. Greene County, formed in 1796 from parts of Washington County.
31. Huntingdon County, formed in 1787 from parts of Bedford County.
32. Indiana County, formed in 1803 from parts of Lycoming and Westmoreland Counties; it was attached to Westmoreland County until 1806.
33. Jefferson County, formed in 1804 from parts of Lycoming County. Attached to Westmoreland County until 1806 and to Indiana County until 1830.
34. Juniata County, formed 1831 from parts of Mifflin County.
35. Lackawanna County, formed in 1878 from parts of Luzerne County.
36. Lancaster County, formed in 1729 from parts of Chester County.
37. Lawrence County, formed in 1849 from parts of Beaver and Mercer Counties.
38. Lebanon County, fourmed in 1813 from parts of Dauphin and Lancaster Counties.
39. Lehigh County, formed in 1812 from parts of Northampton County.
40. Luzerne County, formed in 1786 from parts of Northumberland County.
41. Lycoming County, founed in 1795 from parts of Northumberland County.
42. McKean County, formed in 1804 from parts of Lycoming County; Attached to Centre County until 1814 and to Lycoming County until 1826 for judicial and elective purposes. McKean was fully organized only in 1826.
43. Mercer County, formed in 1800 from parts of Allegheny County.
44. Mifflin County, formed in 1789 from parts of Cumberland and Northumberland Counties.
45. Monroe County, formed in 1836 from parts of Pike and Northampton Counties.
46. Montgomery County, formed in 1784 from parts of Philadelphia County.
47. Montour County, formed in 1850 from parts of Columbia County.
48. Northampton County, formed in 1752 from parts of Bucks County.
49. Northumberland County, formed in 1772 from parts of Lancaster, Berks, Bedford, Cumberland, and Northampton Counties.
50. Perry County, formed in 1820 from parts of Cumberland County.
51. Philadelphia County, one of the original counties at the formation of Pennsyvania in 1682. The city and county of Philadelphia were combined in 1854 and city and county offices merged in 1952.
52. Pike County, formed in 1814 from parts of Wayne County.
53. Potter County, Formed in 1804 from Lycoming county. Attached to Lycoming County until 18265 and to McKean County until 1835 for judicial purposes, Potter was not fully organized until 1835.
54. Schuylkill County, formed in 1811 from parts of Berks and Northampton Counties.
55. Snyder County, formed in 1855 from parts of Union County.
56. Somerset County, formed in 1795 from parts of Bedford County.
57. Sullivan County, formed in 1847 from parts of Lycoming County; attached to Lycoming until 1848.
58. Susquehanna County, formed in 1810 from parts of Luzerne County ; attached to Luzerne County until 1812.
59. Tioga County, formed in 1804 from parts of Lycoming County; attached to Lycoming until 1812.
60. Union County, formed in 1813 from parts of Northumberland County.
61. Venango County, formed in 1800 from parts of Allegheny and Lycoming Counties; attached to Crawford Count until 1805.
62. Warren County, formed in 1800 from parts of Allegheny and Lycoming counties; attached to Crawford County until 1805 and then to Venango until Warren was formally organized in 1819.
63. Washington County, formed in 1781 from parts of Westmoreland County
64. Wayne County, formed in 1798 from parts of Northampton County.
65. Westmoreland County, formed in 1773 from parts of Bedford County.
66. Wyoming County, formed in 1842 from parts of Luzerne County.
67. York County, formed in 1749 from parts of Lancaster County.