The Wikipedia article of the day for January 6, 2017 is Clinton Engineer Works.
The Clinton Engineer Works was the site of the Manhattan Project's World War II production facilities that provided the enriched uranium used in the bombing of Hiroshima in August 1945. Its X-10 Graphite Reactor produced the first samples of plutonium from a reactor. Located just south of the town of Clinton, Tennessee, it included the production facilities of the K-25, Y-12 and S-50 projects, various utilities, and the township of Oak Ridge. The Manhattan District Engineer, Kenneth Nichols, moved the Manhattan District headquarters there from Manhattan in August 1943. Many construction workers were housed in large temporary communities, including Happy Valley. The construction labor force peaked at 75,000. Oak Ridge was established to house the operating staff, which peaked at 50,000 workers just after the war. It was developed by the federal government as a segregated community; black residents lived in an area known as Gamble Valley, in government-built hutments of one-room shacks.