Born out of a small research programme in 1939, the Manhattan Project's roots lay in the United States’ fears that, since the 1930s, Nazi Germany had been trying to develop nuclear weapons. Efforts towards upgrading this project moved forward in 1942, when it was transferred to the authority of the United States Army as the “Manhattan Project”. Formally designated as the Manhattan Engineer District (MED), this project ran from 1941–1946 under the control of the United States Army Corps of Engineers administered by General Leslie R. Groves. The scientific research was directed by American physicist J. Robert Oppenheimer.
Eventually, the Manhattan Project employed more than 130,000 people and cost nearly US$ 2 billion (equivalent to US$ 23 billion in 2007 dollars).
Eventually, the Manhattan Project employed more than 130,000 people and cost nearly US$ 2 billion (equivalent to US$ 23 billion in 2007 dollars). It created multiple secret production and research sites, the three primary ones being: the plutonium-production facility at what is now the Hanford Site (Washington state); uranium-enrichment facilities at Oak Ridge, Tennessee; and the weapons research and design laboratory, now known as Los Alamos National Laboratory in New Mexico. Project research took place at over 30 different sites across the United States, Canada and the United Kingdom. The Manhattan Project maintained control over United States’ weapons production until formation of the US Atomic Energy Commission in January 1947.