LST-57 was laid down on 24 October 1943 at Pittsburgh, Pa., by the Dravo Corp.; launched on 4 December 1943; sponsored by Mrs. Edward Mays; and commissioned on 15 January 1944.
During World War II, LST-57 served in the European theater and participated in the Normandy invasion from 6 to 25 June. Immediately following the war, she was assigned to occupation duty in the Far East during the fall of 1945. She was decommissioned on 24 January 1946 and placed in reserve. On 1 July 1955, LST-57 was named Armstrong County after counties in Pennsylvania and Texas. Her name was struck from the Navy list on 11 August 1955, and she was sunk as a target in 1956.
Armstrong County earned one battle star for World War II service as LST-57.