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 State Guard Guard was in federal service. Prior to the creation of the modern National Guard of the United States, the United States maintained a relatively small professional military and relied on state militias to augment the federal military in times of war. In 1901, the South Dakota Legislature designated the South Dakota State Guard as the organized militia of South Dakota, and required that the state maintain a certain minimum strength of cavalry, artillery, and infantry units. After the passage of the Militia Act of 1903, state militia units were reorganized into National Guard units and operated as a reserve component