Geography of South Dakota of the federal or state government, such as Badlands National Park, Wind Cave National Park, and Custer State Park, are located in the state. In 2011, the population of South Dakota was estimated to be 824,082, and the state ranks fifth-lowest in both total population as well as population density in the United States. Sioux Falls, with a population of just over 170,000, is the largest city in the state. Rapid City ranks as South Dakota's second-largest city, and Pierre is the state capital. Historically a very agricultural state, the service and tourism sectors have grown in economic importance in
South Dakota Highway 21 South Dakota Highway 21 South Dakota Highway 21 (SD 21) is a state highway in the eastern part of the U.S. state of South Dakota. It connects Lake Norden and Hayti, completely within the south-central part of Hamlin County. SD 21 originally extended from the Nebraska state line to the North Dakota state line, completely concurrent with U.S. Route 81 (US 81). By the mid-1930s, only the current part of the highway remained. SD 21 begins at an intersection with SD 28 just northwest of the main part of Lake Norden. It travels to the north. Almost immediately, it crosses