The United States Army Air Corps (USAAC) was the aerial warfare service component of the United States Army between 1926 and 1941. After World War I, as early aviation became an increasingly important part of modern warfare, a philosophical rift developed between more traditional ground-based army personnel and those who felt that aircraft were being underutilized and that air operations were being stifled for political reasons unrelated to their effectiveness. The USAAC was renamed from the earlier United States Army Air Service on 2 July 1926, and was part of the larger United States Army. The Air Corps became the United States Army Air Forces (USAAF) on 20 June 1941, giving it greater autonomy from the Army's middle-level command structure. During World War II, although not an administrative echelon, the Air Corps (AC) remained as one of the combat arms of the Army until 1947, when it was legally abolished by legislation establishing the Department of the Air Force.

The Air Corps was renamed by the United States Congress largely as a compromise between the advocates of a separate air arm and those of the traditionalist Army high command who viewed the aviation arm as an auxiliary branch to support the ground forces. Although its members worked to promote the concept of air power and an autonomous air force in the years between the world wars, its primary purpose by Army policy remained support of ground forces rather than independent operations.

On 1 March 1935, still struggling with the issue of a separate air arm, the Army activated the General Headquarters Air Force for centralized control of aviation combat units within the continental United States, separate from but coordinate with the Air Corps. The separation of the Air Corps from control of its combat units caused problems of unity of command that became more acute as the Air Corps enlarged in preparation for World War II. This was resolved by the creation of the Army Air Forces (AAF), making both organizations subordinate to the new higher echelon.

On 20 June 1941, the Army Air Corps' existence as the primary air arm of the U.S. Army changed to that of solely being the training and logistics elements of the then-new United States Army Air Forces, which embraced the formerly-named General Headquarters Air Force under the new Air Force Combat Command organization for front-line combat operations; this new element, along with the Air Corps, comprised the USAAF.

The Air Corps ceased to have an administrative structure after 9 March 1942, but as "the permanent statutory organization of the air arm, and the principal component of the Army Air Forces," the overwhelming majority of personnel assigned to the AAF were members of the Air Corps.

The U.S. Army Air Service had a brief but turbulent history. Created during World War I by executive order of President Woodrow Wilson after America entered the war in April 1917 as the increasing use of airplanes and the military uses of aviation were readily apparent as the war continued to its climax, the U.S. Army Air Service gained permanent legislative authority in 1920 as a combatant arm of the line of the United States Army. There followed a six-year struggle between adherents of airpower and the supporters of the traditional military services about the value of an independent Air Force, intensified by struggles for funds caused by skimpy budgets, as much an impetus for independence as any other factor.

The Lassiter Board, a group of General Staff officers, recommended in 1923 that the Air Service be augmented by an offensive force of bombardment and pursuit units under the command of Army general headquarters in time of war, and many of its recommendations became Army regulations. The War Department desired to implement the Lassiter Board's recommendations, but the administration of President Calvin Coolidge chose instead to economize by radically cutting military budgets, particularly the Army's. The Lampert Committee of the House of Representatives in December 1925 proposed a unified air force independent of the Army and Navy, plus a department of defense to coordinate the three armed services. However another board, headed by Dwight Morrow, was appointed in September 1925 by Coolidge ostensibly to study the "best means of developing and applying aircraft in national defense" but in reality to minimize the political impact of the pending court-martial of Billy Mitchell (and to preempt the findings of the Lampert Committee). It declared that no threat of air attack was likely to exist to the United States, rejected the idea of a department of defense and a separate department of air, and recommended minor reforms that included renaming the air service to allow it "more prestige".

In early 1926 the Military Affairs Committee of the Congress rejected all bills set forth before it on both sides of the issue. They fashioned a compromise in which the findings of the Morrow Board were enacted as law, while providing the air arm a "five-year plan" for expansion and development. Maj. Gen. Mason Patrick, the Chief of Air Service, had proposed that it be made a semi-independent service within the War Department along the lines of the Marine Corps within the Navy Department, but this was rejected; only the cosmetic name change was accepted. The legislation changed the name of the Air Service to the Air Corps, (in the words of one analyst) "thereby strengthening the conception of military aviation as an offensive, striking arm rather than an auxiliary service."