Minuteman Missile National Historic Site was established in 1999 to illustrate the history and significance of the Cold War, the arms race, and intercontinental ballistic missile (ICBM) development. This National Historic Site preserves the last remaining Minuteman II ICBM system in the United States. (450 of the newer Minuteman III missiles are still on active duty, at Malmstrom AFB, MT, Minot AFB, ND and F. E. Warren AFB, WY.) This National Historic Site consists of three facilities: a main office and two significant Cold War-era sites, a launch control center and a missile silo/launch facility, formerly operated by the 66th Strategic Missile Squadron of the 44th Strategic Missile Wing, headquartered at Ellsworth Air Force Base in Rapid City, South Dakota. The facilities represent the only remaining intact components of a nuclear missile field that once consisted of 150 Minuteman II missiles, 15 launch control centers, and covered over 13,500 square miles (35,000 km2) of southwestern South Dakota.