Established by the United States government on the Columbia River in southeastern Washington in 1943 as part of the Manhattan Project, the Hanford Engineer Works became the first full-scale industrial plutonium production site. Its B Reactor produced plutonium used in the Trinity test and the Fat Man bomb dropped on Nagasaki. Built on a vast scale with abundant water and power, the complex displaced about 1,500 residents and employed nearly 45,000 workers at peak construction. Hanford continued producing plutonium for nuclear weapons until 1971, and its history embodies both the immense industrial effort and the human consequences of the early nuclear age.