Black Elk Peak, formerly named Harney Peak, with an elevation of , is the state's highest point, while the shoreline of Big Stone Lake is the lowest, with an elevation of . South Dakota is bordered to the north by North Dakota; to the south by Nebraska; to the east by Iowa and Minnesota; and to the west by Wyoming and Montana. The geographical center of the U.S. is west of Castle Rock in Butte County. The North American continental pole of inaccessibility is between Allen and Kyle, from the nearest coastline.