U.S. Secretary of State William H. Seward and Russian minister Eduard de Stoeckl signed the treaty ceding Russia’s North American possessions (Alaska) to the United States for $7.2 million, setting the legal basis for U.S. sovereignty.
After U.S. Senate ratification, the governments exchanged ratifications and the United States proclaimed the treaty, triggering transfer provisions that made the cession operative under the agreement.
Commissioners from Russia and the United States conducted the public transfer ceremony at Sitka (Castle Hill/Fort Sitka), marking the on-the-ground change in sovereignty commemorated as Alaska Day.
Congress passed (and President Chester A. Arthur signed) the First Organic Act, establishing the District of Alaska with a civil government and judicial district—an important shift away from purely military administration.
The Second Organic Act established a territorial government for Alaska, replacing the District structure and expanding local civil institutions under U.S. territorial governance.
Congress authorized the federal government to locate, construct, and operate a railroad in Alaska, launching major federally directed territorial infrastructure development.
President Warren G. Harding created Naval Petroleum Reserve No. 4 on Alaska’s North Slope (later the National Petroleum Reserve–Alaska), reserving a vast area for potential naval fuel supply and shaping future federal land and energy policy in Alaska.
The U.S. Army Corps of Engineers officially commenced construction of the Alaska Highway in 1942, creating a strategic overland supply route linking Alaska to the rest of North America through Canada.
Japanese carrier aircraft attacked Dutch Harbor on June 3–4, 1942, bringing World War II directly to Alaska and accelerating military construction, logistics, and security development across the territory (including the Aleutian campaign and evacuations).
Congress approved legislation providing for Alaska’s admission to the Union, contingent on acceptance of the Act’s terms by Alaskans and completion of required steps toward statehood.
President Dwight D. Eisenhower issued the proclamation admitting Alaska to the Union as the 49th state, completing the territory-to-state transition begun decades earlier.
President Richard Nixon signed ANCSA into law, extinguishing aboriginal land claims in exchange for land conveyances and financial compensation through newly created Alaska Native regional and village corporations—fundamentally reshaping Alaska land ownership and governance.
The Naval Petroleum Reserves Production Act transferred Naval Petroleum Reserve No. 4 from the Navy to the Department of the Interior and redesignated it as the National Petroleum Reserve in Alaska, changing long-term administration of a major North Slope federal land unit.
President Jimmy Carter signed ANILCA, designating and expanding national parks, wildlife refuges, wilderness, and other protected lands in Alaska—one of the largest conservation actions in U.S. history.
Alaska Purchase and Territorial Development (1867–1959)
