What date marks the establishment of the USAF as a separate branch?

The establishment of the United States Air Force (USAF) as a separate branch of the military occurred on 18 September 1947. This date is significant because it follows the National Security Act of 1947, which transformed the Army Air Forces into a distinct service, recognizing the importance of air power as essential for national defense. The creation of the USAF also reflected the changing nature of warfare in the post-World War II era, where air superiority became increasingly critical.

The other dates mentioned refer to different milestones in aviation and military history. While July 1926, June 1941, and August 1990 are important, they do not represent the official establishment of the USAF as an independent branch, making September 18, 1947 the correct and pivotal date for this transition.