The United States had become the arsenal of the European powers during the Second World War. There is even a book written by Paul A. C Kioistinen that is titled "Arsenal of World War II: The Political Economy of American Warfare 1940-1945". The obvious reason for this was that the Axis Air Forces, especially the Luftwaffe of Hitler under its Blitzkrieg or lightning warfare had bombed out a majority of the industrial centres of the allied nations in Europe.
Even the then ally of the Allied forces the Soviet Union had its industries bombed to a catastrophic extent. The distance at which America lay and the late stage at which entered the war allowed its territory to remain untouched by bombings. In fact the first time the American people saw a military kind of strike on their territory was the terrorist attacks on the World Trade Centre. America even help arm the Soviet Union to help with the eastern front.
Even the then ally of the Allied forces the Soviet Union had its industries bombed to a catastrophic extent. The distance at which America lay and the late stage at which entered the war allowed its territory to remain untouched by bombings. In fact the first time the American people saw a military kind of strike on their territory was the terrorist attacks on the World Trade Centre. America even help arm the Soviet Union to help with the eastern front.