The United States purchased Alaska from the Russian Empire in 1867 for $7.2 million, a deal negotiated by Secretary of State William Seward. Often referred to as "Seward's Folly," the 1867 treaty transferred 586,412 square miles of land to the U.S.. The purchase allowed Russia to divest of a hard-to-defend territory and bolstered U.S. expansion in the Pacific. Key Details of the Alaska Purchase (1867): Sign Date: March 30, 1867. Final Transfer: October 18, 1867. Price: $7.2 million (approximately 2 cents per acre). Significance: Ended Russian presence in North America and added vast natural resources (gold, oil, seafood) to the U.S..