Lineage. Constituted as 21 Fighter Squadron, Single Engine, on 5 Oct 1944. Activated on 15 Oct 1944. Inactivated on 15 Oct 1946. Redesignated as 21 Fighter-Day Squadron on 26 Aug 1954. Activated on 11 Nov 1954. Redesignated as 21 Tactical Fighter Squadron on 1 Jul 1958. Inactivated on 15 Mar 1959.