Gettysburg, South Dakota was named for the Pennsylvania battlefield by a group of Union Civil War veterans who first settled here. Founded in 1881 and platted in 1884, Gettysburg is the county seat of Potter County. Gettysburg has a wide trade area that is visited by farmers, ranchers, and the Cheyenne Sioux Indian reservation population. The Cheyenne Agency, headquarters for the officials of the Cheyenne River Reservation lies close by. The reservation covers parts of three counties.