Johnston Atoll, located in the North Pacific 1,151 km (715 mi) sw of Honolulu, consists of two islands, Johnston (16° 44′ n and 169° 31′ w) and Sand (16° 45′ n and 169° 30′ w), with a total land and water area of about 2.6 sq km (1 sq mi). The islands are enclosed by a semicircular reef. It was discovered by English sailors in 1807 and claimed by the United States in 1858. For many years, it was worked for guano and was a bird reservation.
Commissioned as a naval station in 1941, it remains an unincorporated US territory under the control of the US Department of the Air Force. In recent years, it has been used primarily for the testing of nuclear weapons.
As of January 2003, there were about 800 people living on the atoll; the population, usually standing at 1,100 government personnel and contractors, decreased significantly after the September 2001 departure of the US Army Chemical Activity Pacific (USACAP). The atoll is equipped with an excellent satellite and radio telecommunications system.