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 15 South Dakota Highway 15 South Dakota Highway 15 (SD 15) is a state highway in the northeastern part of the U.S. state of South Dakota. It connects Clear Lake, Milbank, and Wilmot. SD 15 originally traveled from the Nebraska state line to the North Dakota state line. It followed what would eventually become U.S. Route 77 (US 77), which had been designated before 1931. Part of its path went north from Wilmot to Sisseton, then north to Hammer, along US 81's former path, west to Claire City, north to the North Dakota state line north of Claire City, where it