Russia transferred Alaska to the United States in 1867.
The agreement is known as the Alaska Purchase. Secretary of State William H. Seward negotiated the treaty with Russia, and the United States paid $7.2 million, equivalent to about two cents per acre at the time. The formal transfer ceremony took place at Sitka on October 18, 1867, a date now observed in Alaska as Alaska Day.
Russia was willing to sell partly because its North American colony was difficult to supply and defend, especially after the Crimean War. Russian officials also feared that Britain might seize the territory in a future conflict. The United States saw strategic and commercial value in gaining control of the vast region.
Some Americans mocked the purchase as “Seward’s Folly,” but later discoveries of gold, oil, and other resources changed public opinion. Alaska became a U.S. territory in 1912 and the 49th state in 1959. It remains the largest U.S. state by area.