| Twenty-First Air Force | |
|---|---|
 Shield of the Twenty-First Air Force | |
| Active | 18 June 1942 – 19 March 2012 (69 years, 9 months) |
| Country |  United States |
| Branch |  United States Air Force |
| Part of | Air Mobility Command |
| Engagements | .png){kind=small} World War II – American Theater |
| Decorations |  Air Force Outstanding Unit Award (19x) |
| Insignia | |
| 21st Expeditionary Mobility Task Force emblem |  |
The Twenty-First Air Force (21 AF) is an inactive numbered air force of the United States Air Force. It was last active as the 21st Expeditionary Mobility Task Force (21 EMTF), stationed at the McGuire AFB entity of Joint Base McGuire–Dix–Lakehurst until its inactivation in 2012. In this capacity, it was subordinate to Air Mobility Command's Eighteenth Air Force.
First created as a wing of the United States Army Air Forces during World War II, the unit initially ferried aircraft, but its mission soon changed to airlifting personnel and cargo.
The organization was redesignated several times, eventually becoming the Twenty-First Air Force in 1966.
In 2003, the unit was redesignated as the 21st Expeditionary Mobility Task Force, assuming responsibility for worldwide airlift operations in support of United States Joint Forces Command, United States European Command, and United States Central Command.
In 2012, the organization was inactivated, with its subordinate units and responsibilities being transferred to the United States Air Force Expeditionary Center.