Hanford Site is a vast former nuclear production complex on the Columbia River in Washington, created in 1943 for the Manhattan Project because of its isolation, water, and hydroelectric power. Its B Reactor was the world’s first full-scale plutonium production reactor, and plutonium made here was used in the Trinity test and the bomb dropped on Nagasaki. During the Cold War, Hanford expanded into a major center of U.S. weapons production, then became a stark example of the environmental damage caused by early nuclear work. After its reactors closed, it became the focus of the nation’s largest environmental cleanup effort while remaining a place of deep Native history, scientific research, and public memory.