The Alaska Purchase (Russian: Продажа Аляски, tr. Prodazha Alyaski) was the United States' acquisition of Alaska from the Russian Empire in 1867 by a treaty ratified by the United States Senate.

Russia wanted to sell its Alaskan territory, fearing that it might be seized if war broke out with Britain. Russia's primary activities in the territory had been fur trade and missionary work among the Native Alaskans. The land added 586,412 square miles (1,518,800 km2) of new territory to the United States.

Reactions to the purchase in the United States were mostly positive, with some opponents calling it "Seward's Folly" (after Secretary of State William H. Seward), while many others praised the move for weakening both Britain and Russia as rivals to American commercial expansion in the Pacific region. The purchase threatened British control of its Pacific coast colony, giving added impetus to Canadian Confederation, which was realized just three months later, in July 1867. The Dominion of Canada would welcome British Columbia to confederation in 1871, ending US hopes of annexation and an uninterrupted connection of Alaska to the United States.

Originally organized as the Department of Alaska, the area was renamed the District of Alaska and the Alaska Territory before becoming the modern state of Alaska upon being admitted to the Union as a state in 1959.

In the picture - William H. Seward.

More Info: en.wikipedia.org