In September 1939,at the outbreak of war in Europe, the Air Corps of the United States had a strength of 26,000 personnel and less than 2,000 aircraft. However, from that date the Department of War began a steady growth in the air element and on June 20th 1941, the United States Army Air Force (USAAF) was formed .
In December 1941, the United States entered the war following the attack on it's base at Pearl Harbour, and as a result expansion of the USAAF was stepped up until at it's peak, it numbered in excess of 2,000,000 personnel and 80,000 aircraft including such famous names as the C47 'Skytrain', (or Dakota as it became known in the UK), the P51 'Mustang' and the B17 'Flying Fortress'.
From it's entry into the conflict until the war ended in 1945, when the first atomic bombs were dropped from B29 'Superfortresses' of the USAAF on the cities of Nagasaki and Hiroshima, USAAF units were involved in operations in every theatre of the war including the islands of the Pacific, the icy waters of the North Atlantic and the air war over Europe.
By 1945, the USAAF was the major element in the allied air power which dominated the skies over both Europe and Japan, and it's contribution to the eventual victory cannot be over-estimated.
The sheer scale of the size and operations of the USAAF cannot be covered in the few words written here, or indeed within this site, and I would therefore recommend that, should you like more information, you visit the "USAF Museum" website which can be accessed from our links page.