Corson County, South Dakota

thumb|[[Triceratops skull from Corson County. Collections of Houston Museum of Natural Science.]]

Corson County is a county in the U.S. state of South Dakota. As of the 2020 census, the population was 3,902. Its county seat is McIntosh. The county was named for Dighton Corson, a native of Maine, who came to the Black Hills in 1876, and in 1877 began practicing law at Deadwood.

The county is encompassed within the Standing Rock Sioux Reservation, which extends into North Dakota. The Lakota people reside primarily in the South Dakota part of the reservation; the Yanktonai and Dakota live in that part in North Dakota. The Grand River, a tributary of the Missouri River, runs through the reservation.

Geography

Corson County lies on the north line of South Dakota. Its north boundary line abuts the south boundary line of the state of North Dakota. The Missouri River flows south-southeastward along its eastern boundary line. The county terrain consists of semi-arid rolling hills. A portion of the land is dedicated to agriculture. The Grand River flows eastward through the central part of the county to discharge into the river, and Standing Cloud Creek flows eastward through the county's lower SW area. The terrain generally slopes to the east and south; its highest point is near its NW corner, at ASL.

Corson County has a total area of , of which is land and (2.4%) is water. It is the fifth-largest county in South Dakota by area. The entire county lies within the Standing Rock Sioux Reservation, which also includes Sioux, Ziebach, and Dewey counties.

The eastern portion of South Dakota's counties (48 of 66) observe Central Time; the western counties (18 of 66) observe Mountain Time. Corson County is the easternmost of the SD counties to observe Mountain Time.

Major highways

20px U.S. Highway 12
20px South Dakota Highway 20
20px South Dakota Highway 63
20px South Dakota Highway 65
23px South Dakota Highway 1806

Adjacent counties

Sioux County, North Dakota – north (eastern half of county observes Central Time)
Campbell County – east (observes Central Time)
Walworth County – southeast (observes Central Time)
Dewey County – south
Ziebach County – southwest
Perkins County – west
Adams County, North Dakota – northwest

Protected areas

Grand River National Grassland (partial)
C.C. Lee State Game Production Area

Lakes

Mallard
McGee
McIntosh
Morristown East
Morristown West
Lake Oahe (part)
Pudwell
Trail City

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The population density was . There were 1,362 housing units, of which 12.2% were vacant. Among occupied housing units, 56.0% were owner-occupied and 44.0% were renter-occupied. The homeowner vacancy rate was 0.4% and the rental vacancy rate was 4.0%.

Of the 1,196 households, 41.8% had children under the age of 18 living with them and 27.5% had a female householder with no spouse or partner present. About 27.1% of all households were made up of individuals and 9.6% had someone living alone who was 65 years of age or older.

Snake Creek
Thunder Hawk
Trail City
Walker
Watauga

Townships

Custer
Delaney
Lake
Mission
Pleasant Ridge
Prairie View
Ridgeland
Rolling Green
Sherman
Wakpala
Watauga

Unorganized territories

Central Corson
Lemmon No. 2
Northeast Corson
West Corson

Politics

In the 2020 presidential election, Corson County was the county or equivalent with the highest percentage of Native Americans which Donald Trump won, after Joe Biden flipped Ziebach County.