In the United States Air Force, a division was an intermediate level of command, subordinate to a numbered air force, controlling one or more wings. It also controlled squadrons without associated same-function wings, i.e., 17th Defense Systems Evaluation Squadron had no associated wing, but its function was part of the 24th Air Division. Divisions are now considered obsolete. History On 16 September 1947, the United States Army Air Forces became the United States Air Force as a separate and equal element of the United States armed forces. Earlier, on 21 March 1946, General Carl A. Spaatz had undertaken a major reorganization of the Army Air Forces that had included the establishment of the major command echelon as the first level of command below Headquarters, USAAF. The World War II commands, which had been subordinate to the numbered air forces, were eliminated in the reorganization of 1946, and the Numbered Air Forces were made components of the major commands at home and overseas. The new organizational hierarchy thus contained the following levels : squadron, group, wing, air force, command. In 1948, and afterward, the World War II wings were redesignated "divisions", and placed immediately below the numbered air forces in the organizational pyramid. The "wing" was redefined to be the USAF basic organizational unit which exercised command and control over a "Base", the physical facility that included the airfield and the support units (groups, squadrons) to support the operation of a wing. In the years after 1948, the Air Force "division" carried several designations of the name "strategic aerospace division"; "strategic missile division"; "space division", however the most common designation was "air division". Usage Air divisions were found in all major commands between 1948 and 1992, when the last air division was inactivated. Official policy dictated the use of Arabic numerals for numbered air and aerospace divisions. Examples: 2nd Air Division, 7th Air Division, and 1st Strategic Aerospace Division. Following the initiation of major command-controlled (MAJCON) four-digit Table of Distribution (T/D) organizations in 1948, the major commands were briefly authorized to organize air divisions, provided they secured USAF approval. Two four-digit air divisions (4310th Air Division and 7217th Air Division) were subsequently organized. Besides numbered air divisions, a named air division was an organization within a large support command that was assigned a major or important segment of that command's mission—e.g., the Electronic Systems Division handled a large part of the