Riverbank Army Ammunition Plant is located just outside Riverbank, California, in Stanislaus County. The facility was built in 1942 as an aluminum reduction plant operated by Alcoa producing 48,000 tons per year for World War II aircraft manufacture until 1944. It was reactivated in 1951 for the Korean War and was the United States' largest producer of steel cartridge cases until 1958. It reopened in 1966 manufacturing mortar shells and projectiles for the Vietnam War and remained in production until 1981. The facility includes 192 buildings on 172 acres (0.70 km2).