when did the military start using social security numbers
Service number (United States Armed Forces) Service numbers were eventually phased out completely by the social security number; the Army and Air Force converted to social security numbers on 1 July 1969, the Navy and Marine Corps on 1 January 1972, and the Coast Guard on 1 October 1974.[4] Since that time, social security numbers have become the de facto military service number for United States armed forces personnel.