Located in southwestern South Dakota along the boundary with Nebraska, 72 km (45 mi) southeast of Rapid City; County Seat: Hot Springs.
Created in 1875 and originally named for Peter Shannon (1821-1899), Chief Justice of the Dakota Territory Supreme Court from 1873 to 1882. On November 4, 2014, residents voted to changed the name to Oglala Lakota County (SD House Joint Resolution No. 1005). The name change became effective March 5, 2015.