South Dakota is a state in the north-central region of the United States, and is considered a part of the Midwest by the U.S. Census Bureau. It is also part of the Great Plains. The state is bordered by North Dakota to the north, Minnesota and Iowa to the east, Nebraska to the south, and Wyoming and Montana to the west. South Dakota is named after the Dakota Sioux Native American tribe, which comprises a large portion of the population with nine reservations currently in the state and has historically dominated the territory. The state is split by the upper Missouri River valley into eastern and western regions. The capital of South Dakota is Pierre, and the largest city is Sioux Falls.