The U.S. Air Force Birthday is observed worldwide every September 18, commemorating the establishment of the U.S. Air Force as a separate branch of the armed forces in 1947. The origins of the Air Force can be traced back to the Aeronautical Division of the U.S. Signal Corps, established in 1907, which evolved through various forms, including the Army Air Service and the Army Air Corps, before becoming the United States Air Force. Although not a federal holiday, the occasion is widely celebrated in the military and by veteran organizations. Activities often include free admission to military history museums for Air Force personnel and veterans, as well as social media engagement using the hashtag #AirForceBirthday. The core missions of the Air Force include aerial supremacy and global strike, reflecting its significant role in various military operations and humanitarian efforts.