Badlands National Park in southwestern South Dakota protects 242,756 acres of eroded buttes, pinnacles, and mixed-grass prairie in the White River drainage, including the nation’s largest undisturbed mixed-grass prairie. Known to the Lakota as Makȟóšiča, or “bad lands,” it has been used by people for about 11,000 years, from Paleo-Indians to the Arikara and Lakota. The South Unit on the Pine Ridge Reservation is co-managed with the Oglala Lakota and includes the sacred Stronghold District, site of one of the last Ghost Dances before Wounded Knee. The area is also a major fossil field, famed since the 19th century for Oligocene mammals, and later became a national monument and then a national park.