Although the United State Air Force’s Air Defense Com-mand was officially stood up on 21 March 1946, the origins of its component forces date back to the War Department’s establishment of an Air Defense Command on 26 February 1940 comprising four regional Air Districts. On 16 January 1941, the Headquarters and Headquarters Squadrons of the Northeast, Northwest, Southeast, Southwest Air Districts were activated, and on 26 March 1941 the Districts were redesignated as numbered Air Forces (1st through 4th, respectively).
The four Air Forces became the basis of the Continental Air Forces (CAF), activated on 12 December 1944. In March 1946 it was replaced by the U.S. Army Air Force’s Air Defense Command, which initially comprised the CAF’s Fourth Air Force and the USAAF’s Tenth and Fourteenth Air Forces; the CAF’s Second Air Force was added to the Command in June.
This iteration of the Air Defense Command was soon subordinate to the Continental Air Command (CAC), established in 1948, and by 1950 CAC seemed to make Air Defense Command unnecessary and it was inactivated after less than five years in existence. Air Defense Command was reactivated in 1951, and was redesignated as Aerospace Defense Command in 1968. The newly designated command used an emblem highly similar to its predecessor’s, but with two changes: two ellipses indicating orbital paths passing over the North Pole were superimposed over the globe, which was reoriented to display the North American continent and the Soviet Union rather than just the United States, Canada, and Alaska.
Following the redesignation, the increasing use of Air Force Reserve (also created in 1968) and Air National Guard units for the conduct of the air defense mission made the Aerospace Defense Command increasingly redundant, and in 1980 it was permanently inactivated.