The official birthday of the United States Air Force is September 18, 1947. This date marks the formal establishment of the Air Force as an independent branch of the U.S. Armed Forces. The creation of a separate air service culminated decades of advocacy by air power proponents who argued for an organization focused solely on aerial warfare. This independence signified a major shift in the nation’s defense structure, recognizing the importance of air power in the modern era. The date is celebrated annually to commemorate the Air Force’s separation from the U.S. Army.
The Official Founding Date and Legislation
The establishment of the Air Force was tied to the passage of the National Security Act of 1947. President Harry S. Truman signed this legislation into law on July 26, 1947, initiating a major restructuring of the U.S. military following World War II. The act created the National Military Establishment and formally merged the Departments of the Army and the Navy with the newly created Department of the Air Force.
The specific date of September 18, 1947, was chosen because it was the day the majority of the act’s provisions took effect. On this day, W. Stuart Symington was sworn in as the first Secretary of the Air Force, establishing the civilian leadership for the new service. The act mandated the transfer of personnel, property, and functions from the Army Air Forces (AAF) to the new Department of the Air Force.
The AAF was formally abolished on September 18, 1947, with its assets forming the foundation of the new Air Force. This separation was a significant organizational change, moving the air component from a combat arm within the Army to a fully autonomous service. The National Security Act of 1947 defined the Air Force’s primary mission as being organized, trained, and equipped for “prompt and sustained offensive and defensive air operations.”
The Air Force’s Pre-Independence Lineage
The history of U.S. military aviation extends back four decades before the Air Force’s 1947 independence. The earliest antecedent was the Aeronautical Division of the U.S. Army Signal Corps, established on August 1, 1907. This small division was tasked with managing all matters related to military ballooning and “air machines.”
The division procured the Army’s first powered military aircraft, the Wright Military Flyer, in 1909, and later formed the first permanent American aviation unit, the 1st Aero Squadron, in 1913. The air arm underwent several name changes while remaining a component of the Army, reflecting its growing importance. It transitioned from the Aeronautical Division to the Aviation Section of the Signal Corps in 1914, and then to the Air Service, U.S. Army, in 1918.
In 1926, the organization was renamed the U.S. Army Air Corps, and in 1941, it became the U.S. Army Air Forces (AAF). Despite these changes, the air arm remained under the control of the Army, with its primary purpose often viewed as supporting ground forces. The AAF achieved a high degree of autonomy during World War II, setting the stage for the complete independence realized with the 1947 legislation.