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 168 maintained by SDDOT. In 2012, the traffic on the highway was measured in average annual daily traffic. The route had an average of 165 vehicles. The designation is not a part of the National Highway System, a system of highways important to the nation's defense, economy, and mobility. The Unofficial South Dakota Highways Page South Dakota Highway 168 South Dakota Highway 168 (SD 168) is a state highway in Butte County in the U.S. state of South Dakota. It runs from U.S. Route 85 (US 85) to SD 79. The highway is maintained by the South Dakota Department of Transportation