South Dakota is named after the Lakota and Dakota Sioux American Indian tribes. It is the 17th most extensive, but the 5th least populous and the 5th least densely populated of the 50 United States. Once the southern portion of the Dakota Territory, South Dakota became a state on November 2, 1889. Pierre is the state capital and Sioux Falls, with a population of nearly 160,000, is South Dakota's largest city.
South Dakota is bordered by the states of North Dakota, Minnesota, Iowa, Nebraska, Wyoming, and Montana. The state is bisected by the Missouri River, dividing South Dakota into two geographically and socially distinct halves, known to residents as "East River" and "West River." Eastern South Dakota is home to most of the state's population, and fertile soil in this area is used to grow a variety of crops. West of the Missouri, ranching is the predominant agricultural activity, and the economy is more dependent on tourism and defense spending.