Almost one third of the region west of the Missouri River, a semiarid, treeless plain, belongs to Native Americans, most of whom live on reservations such as Cheyenne River, Pine Ridge, Rosebud, and Standing Rock. Much of the remaining area is occupied by large ranches; there cattle and sheep ranching provide the major source of income, with soybean and wheat farming second in the production of revenue. In the more productive region east of the Missouri, livestock and livestock products are the primary sources of income. Corn, soybeans, oats, and wheat are South Dakota's chief cash crops; sunflowers, sorghum, flaxseed, and barley are also grown. Although there is a certain amount of diversified industry, including electronics manufacturing, in Sioux Falls and Rapid City, meatpacking and food processing are by far the major industries of the state.
Gold is South Dakota's most important mineral, and the town of Lead in the Black Hills is the country's leading gold-mining center. Tourism, focusing especially on Mt. Rushmore and other Black Hills sites, and gambling are also major sources of income.