The Signal Corps began testing its first airplane at Fort Myer, Virginia, on August 20, 1908, and on September 9, Lt Thomas E. Selfridge, flying with Orville Wright, was killed when the plane crashed. Subsequently, after more testing with a second, improved Wright Flyer, the Army formally accepted this airplane, identified as "Airplane No. 1," on August 2, 1909. On May 20, 1918, President Woodrow Wilson issued an executive order transferring aviation from the Signal Corps to two agencies under the Secretary of War: the Bureau of Aircraft Production, and the Division of Military Aeronautics. Despite a combat record of only nine months (February to November 1918), the Air Service made a respectable showing during World War I.

The Army Reorganization Act of 1920 made the Air Service a combatant arm of the Army and gave the Chief of the Air Service the rank of major general and his assistant chief the rank of brigadier general. The Air Corps Act of 1926 changed the name of the Air Service to Air Corps, but left unaltered its status as a combatant arm of the U.S. Army. On March 1, 1935, the General Headquarters Air Force (GHQAF), became operational and assumed command and control over Air Corps tactical units. Early in 1941, the War Department instituted a series of actions to create a hierarchy for noncombat activities. It set up a command eventually designated Flying Training Command to direct new programs for training ground crews and technicians.

A War Department reorganization on March 9, 1942, created three U.S. Army Commands: Army Ground Forces, Services of Supply (later, in 1943, Army Service Forces), and Army Air Forces. The United States Air Force (USAF) is the air service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part of the United States Army Signal Corps, the USAF was established as a separate branch of the United States Armed Forces in 1947 with the enactment of the National Security Act of 1947.