Black Hills, a rough region in southwestern South Dakota and Wyoming. In pioneer days it was a stronghold of the Sioux Indians. The region was opened to settlement in 1876. The Black Hills are noted for mining. Gold, silver, copper, lead, iron, and other ores are produced. The Homestake Mine is the most productive gold mine in North America. There are caves of unknown extent. Grazing is an important industry. See SOUTH DAKOTA.