WWII: U.S. spending on selected explosive weapons programs 1941-1945

After joining the Second World War in 1941, the United States spent approximately 1.89 billion on the Manhattan Project by the end of 1945. The Manhattan Project resulted in the production of the world's first nuclear weapons, and ultimately, two of these weapons were used during the course of the war, in the attacks on Hiroshima and Nagasaki, which led to the Japanese surrender and the end of the Second World War. In total, spending on the Manhattan Project amounted to less than one percent of the United States defense budget, and the production of these two nuclear bombs cost less than the costs of all tanks, artillery, conventional explosives, or light weaponry.