Alaska Purchase
At the instigation of Secretary of State William Seward, the United States Senate approved the purchase of Alaska (about 600,000 square miles) from Russia for $7,200,000 on April 9th, 1867. The treaty was negotiated with Baron Eduard de Stoeckl, Russian minister to the United States.
The purchase was at the time derided as Seward's Folly or Seward's Icebox, because it was believed foolhardy to spend so much money on the land, however, few today would consider it to be a mistake. However, an analysis of the cash flow from the investment compared with the net present value of its purchase price suggests the money could have been invested better elsewhere. [[1]]
Currently, Alaska celebrates the purchase on Seward's Day, the last Monday of March.