|Area||Ranked in the US|
|- Total|| sq mi |
|- Width||miles ( km)|
|- Length||miles ( km)|
|- % water|
|Population||Ranked in the US|
|- Density||/sq mi (/km2)|
Ranked in the US
|- Highest point|
ft ( m)
|- Mean||ft ( m)|
|- Lowest point||ft ( m)|
|Admission to Union||()|
|[[Governor of |Governor]]|
|[[Lieutenant Governor of |Lieutenant Governor]]|
|- Upper house|
|- Lower house|
|[[List of United States Senators from |U.S. Senators]]|
|U.S. House delegation||[[United States congressional delegations from |List]]|
|Abbreviations||List of U.S. state abbreviations#Postal abbreviations List of U.S. state abbreviations#Traditional abbreviations US|
South Dakota () is a state located in the Midwestern region of the United States. It is named after the Lakota and Dakota Sioux American Indian tribes. Once a part of Dakota Territory, South Dakota became a state on November 2, 1889. The state has an area of and an estimated population of just over 800,000. Pierre is the state capital and Sioux Falls, with a population of nearly 160,000, is South Dakota's largest city.
South Dakota is bordered by the states of North Dakota, Minnesota, Iowa, Nebraska, Wyoming, and Montana. The state is bisected by the Missouri River, dividing South Dakota into two geographically and socially distinct halves, known to residents as "East River" and "West River". Eastern South Dakota is home to most of the state's population, and fertile soil in this area is used to grow a variety of crops. West of the Missouri, ranching is the predominant agricultural activity and the economy is more dependent on tourism and defense spending. The Black Hills, a group of low pine-covered mountains, is located in the southwest part of the state. The Black Hills are of great religious importance to local American Indians and the location of Mount Rushmore, a major tourist destination. Other attractions in the southwest include Badlands and Wind Cave national parks, Custer State Park, the Crazy Horse Memorial, and historic Deadwood. South Dakota experiences a temperate continental climate, with four distinct seasons and precipitation ranging from moderate in the east to semi-arid in the west. The ecology of the state features species typical of a North American grassland biome.
Humans have inhabited the area for several millennia, with the Sioux becoming dominant by the early 19th century. In the late 19th century, white settlement intensified after a gold rush in the Black Hills and the construction of railroads in the east. This settlement triggered a number of Indian Wars, ending with the Wounded Knee Massacre in 1890. Key events in the 20th century included the Dust Bowl, increased federal spending during the 1940s and 50s, and continuing changes in agriculture. While several Democratic senators have represented South Dakota for multiple terms at the federal level, the state government is largely dominated by the Republican Party, whose nominees have carried South Dakota in each of the eleven presidential elections. Historically dominated by an agricultural economy and a rural lifestyle, South Dakota has recently sought to diversify its economy to attract and retain residents. However, it is still largely rural and has the fifth-lowest population density among U.S. states. South Dakota's history and rural character still strongly influence the culture of the state.
South Dakota is situated in the north-central United States, and is considered to be a part of the Midwest by the U.S. Census Bureau, although the Great Plains region also covers the state. Additionally, the culture, economy, and geography of western South Dakota has more in common with the West than the Midwest. South Dakota has a total land area of 77,116 sq. miles (199,905 km2), making the state the 17th largest in the Union. Harney Peak, with an elevation of , is the state's highest point, while the shoreline of Big Stone Lake is the lowest, with an elevation of . South Dakota is bordered to the north by North Dakota; to the south by Nebraska; to the east by Iowa and Minnesota; and to the west by Wyoming and Montana. The geographical center of the U.S. is 17 miles (27 km) west of Castle Rock in Butte County.
The Missouri River is the largest and longest river in the state. Other major South Dakota rivers include the Cheyenne, James, Big Sioux, and White Rivers. Eastern South Dakota has many natural lakes, mostly created by periods of glaciation. Additionally, dams on the Missouri River create four large reservoirs: Lake Oahe, Lake Sharpe, Lake Francis Case, and Lewis and Clark Lake.
South Dakota can generally be divided into three regions: eastern South Dakota, western South Dakota, and the Black Hills. The Missouri River serves as a boundary in terms of geographic, social and political differences between eastern and western South Dakota, and the geography of the Black Hills differs from its surroundings to such an extent that it can be considered separate from the rest of western South Dakota. South Dakotans also at times combine the Black Hills with the rest of western South Dakota, and refer to the two resulting regions, divided by the Missouri, as West River and East River.
Eastern South Dakota generally features higher precipitation and lower topography than the western part of the state. Smaller geographic regions of this area include the Coteau des Prairies, the Dissected Till Plains, and the James River Valley. The Coteau des Prairies is a plateau bordered on the east by the Minnesota River Valley and on the west by the James River Basin. Further to the west, the James River Basin is mostly low, flat, highly eroded land, following the flow of the James River through South Dakota from north to south. The Dissected Till Plains, an area of rolling hills and fertile soil that covers much of Iowa and Nebraska, also extends into the southeastern corner of South Dakota. Layers deposited during the Pleistocene epoch, starting around two million years ago, cover most of eastern South Dakota. These are the youngest rock and sediment layers in the state, and are the product of several successive periods of glaciation which deposited a large amount of rocks and soil, known as till, over the area.
The Great Plains cover most of the western two-thirds of South Dakota. West of the Missouri River the landscape becomes more arid and rugged, consisting of rolling hills, plains, ravines, and steep flat-topped hills called buttes. In the south, east of the Black Hills, lie the South Dakota Badlands. Erosion from the Black Hills, marine skeletons which fell to the bottom of a large shallow sea that once covered the area and volcanic material all contribute to the geology of this area.
The Black Hills are in the southwestern part of South Dakota and extend into Wyoming. This range of low mountains covers 6,000 sq. mi (15,500 km²) with peaks that rise from 2,000 to 4,000 feet (600 to 1,200 m) above their bases. The Black Hills are the location of Harney Peak (7,242 ft or 2,207 m above sea level), the highest point in South Dakota and also the highest point in the United States east of the Rocky Mountains. Two billion-year-old Precambrian formations, the oldest rocks in the state, form the central core of the Black Hills. Formations from the Paleozoic Era form the outer ring of the Black Hills; these were created between roughly 540 and 250 million years ago. This area features rocks such as limestone which were deposited here when the area formed the shoreline of an ancient inland sea.
Much of South Dakota, not including the Black Hills, is dominated by a temperate grasslands biome. Although grasses and crops cover most of this region, deciduous trees such as cottonwoods, elms, and willows are common near rivers and in shelter belts. Mammals in this area include bison, deer, pronghorn, coyotes, and prairie dogs. The state bird, the ring-necked pheasant, has adapted particularly well to the area after being introduced from China, and growing populations of bald eagles are spread throughout the state, especially near the Missouri River. Rivers and lakes of the grasslands support populations of walleye, carp, pike, and bass, along with other species. The Missouri River also contains the pre-historic paddlefish.
Because of higher elevation and precipitation, the ecology of the Black Hills differs significantly from that of the plains. The mountains are thickly blanketed by various types of pines, including ponderosa and lodgepole pines, as well as spruces. Black Hills mammals include deer, elk (wapiti), bighorn sheep, mountain goats, and mountain lions, while the streams and lakes contain several species of trout.