Field, New York. The command provided air defense over most of Pennsylvania, New Jersey, New York and the New England area, commanding interceptor and radar stations. Also included were ADCOM radar stations located in Newfoundland, Canada. In addition command of the SAGE DC-03/CC-01 blockhouse was assumed by the 21st AD, as well as CIM-10 Bomarc surface-to-air anti-aircraft missile squadrons near Otis Air Force Base, Massachusetts, Niagara Falls Air Force Missile Site, New York and McGuire Air Force Base, New Jersey. In 1975, a new JCS Unified Command Plan designated Air Defense Command as a specified command and changed its name to the Aerospace Defense Command (ADCOM) on 1 July 1975. The division assumed additional designation 21st ADCOM Region for operational control on 8 December 1978. Air Defense ADCOM was reorganized on 1 October 1979. The atmospheric defense resources (interceptors and warning radars) of ADCOM. including the 21st AD were reassigned to Tactical Air Command (ADTAC). It moved to Griffiss Air Force Base, New York in 1983 when Hancock Field was closed. In 1983, when the air defense mission of CONUS was reassigned to the Air National Guard, the 21st Air Division (ADTAC) was inactivated and its assets transferred to Northeast Air Defense Sector. Lineage Established as the 21st Bombardment Wing on 16 December 1942 Activated on 22 December 1942 Redesignated I Staging Command on 27 September 1945 Inactivated on 3 April 1946 Activated in the Reserve on 20 December 1946 Redesignated: 21st Bombardment Wing, Very Heavy on 31 December 1946 Redesignated: 21st Air Division, Bombardment on 16 April 1948 Inactivated on 27 June 1949 Redesignated 21st Air Division on 5 February 1951 Activated on 16 February 1951 Inactivated on 8 April 1952 Organized on 8 April 1952 Discontinued on 16 October 1952 Activated on 16 October 1952 Redesignated 21st Strategic Aerospace Division on 15 February 1962 Discontinued and inactivated on 1 September 1964 Activated on 20 January 1966 (not organized) Organized on 1 April 1966 Discontinued and inactivated on 31 December 1967 Activated on 19 November 1969 Inactivated on 23 September 1983 Assignments Second Air Force, 22 December 1942 Continental Air Forces, 18 July 1945 Fourth Air Force, 19 November 1945 – 3 April 1946 Fourteenth Air Force, 20 December 1946 Ninth Air Force, 22 December 1948 Fourteenth Air Force, 1 February – 27 June 1949 Fifteenth Air Force, 16 July 1952 Eighth Air Force, 1 July 1955 Second Air