Sully County, South Dakota

Sully County is a county in the U.S. state of South Dakota. As of the 2020 census, the population was 1,446,^[1] making it the fifth-least populous county in South Dakota. Its county seat is Onida.^[2] The county was created in 1873 and organized in 1883.^[3] It is named after General Alfred Sully, who built Fort Sully.^[4]

Sully County is included in the Micropolitan Statistical Area of Pierre.

Sully County was the location of the largest African American homesteader settlement in the state, the Blair Colony. An Illinois man named Norvel Blair arrived in Fairbank Township in 1884, after sending his sons Benjamin and Patrick to investigate the area for settlement.^[5] Blair's financial success, achieved through farming and breeding racehorses, attracted dozens of other Black families to the colony. Blair became the first Black South Dakotan to serve on a school board.

The decline of South Dakota agriculture during the Great Depression led most Blair Colony residents to seek work in larger cities like Minneapolis and Chicago.^[6] A historical marker in the county seat of Onida remembers the colony.^[7]

The west boundary line of Sully County is defined by the meanderings of the Missouri River, which flows southward along its edge. The county's terrain is composed of semi-arid rolling hills, partially devoted to agriculture.^[8] The terrain slopes to the south and east, but the west portion of the county slopes westward into the river valley. The county's highest point is along the midpoint of its north boundary line, at 1,949 ft (594 m) ASL.^[9] The county has a total area of 1,070 square miles (2,800 km²), of which 1,007 square miles (2,610 km²) is land and 63 square miles (160 km²) (5.9%) is water.^[10]

The eastern portion of South Dakota's counties (48 of 66) observe Central Time; the western counties (18 of 66) observe Mountain Time. Sully County is at the western edge of those counties that observe Central Time.^[11]

• U.S. Highway 83
• South Dakota Highway 1804

Source:^[8]

Source:^[8]

As of the 2020 census, there were 1,446 people, 635 households, and 428 families residing in the county.^[17] The population density was 1.4 inhabitants per square mile (0.54/km²).^[18]

Of the residents, 21.2% were under the age of 18 and 22.2% were 65 years of age or older; the median age was 45.4 years. For every 100 females there were 112.0 males, and for every 100 females age 18 and over there were 111.1 males.^{[18] [19]}

The racial makeup of the county was 93.4% White, 0.3% Black or African American, 0.7% American Indian and Alaska Native, 0.4% Asian, 0.6% from some other race, and 4.6% from two or more races. Hispanic or Latino residents of any race comprised 2.9% of the population.^[19]

There were 635 households in the county, of which 28.7% had children under the age of 18 living with them and 14.0% had a female householder with no spouse or partner present. About 26.8% of all households were made up of individuals and 12.1% had someone living alone who was 65 years of age or older.^[18]

There were 892 housing units, of which 28.8% were vacant. Among occupied housing units, 81.9% were owner-occupied and 18.1% were renter-occupied. The homeowner vacancy rate was 0.2% and the rental vacancy rate was 24.8%.^[18]

As of the 2010 census, there were 1,373 people, 610 households, and 397 families in the county. The population density was 1.4 inhabitants per square mile (0.54/km²). There were 845 housing units at an average density of 0.84 units per square mile (0.32 units/km²). The racial makeup of the county was 96.6% white, 1.2% American Indian, 0.1% black or African American, 0.0% from other races, and 2.2% from two or more races. Those of Hispanic or Latino origin made up 0.9% of the population. In terms of ancestry,

Of the 610 households, 27.0% had children under the age of 18 living with them, 57.5% were married couples living together, 4.6% had a female householder with no husband present, 34.9% were non-families, and 31.6% of all households were made up of individuals. The average household size was 2.25 and the average family size was 2.82. The median age was 46.6 years.

The median income for a household in the county was $48,958 and the median income for a family was $58,875. Males had a median income of $34,375 versus $29,087 for females. The per capita income for the county was $26,596. About 4.4% of families and 8.0% of the population were below the poverty line, including 12.8% of those under age 18 and 8.4% of those age 65 or over.

• Onida (county seat)

• Agar

• Cow Creek

The county organization does not include division into townships. Its area is divided into two areas of unorganized territory: West Sully and East Sully.

Throughout its history, Sully County has been powerfully Republican. The solitary Democrat to carry Sully County at a Presidential level has been Franklin D. Roosevelt in 1932 during an election heavily influenced by the "Dust Bowl" and Great Depression. Nonetheless, in the following 1936 election, Alf Landon won the county by over twenty percent. Since that time, the Democratic Party has bettered FDR's 1936 effort five times, but only Lyndon Johnson in 1964 has held the GOP to a single-digit margin. In modern times, like almost all of rural America, Sully County has become more and more Republican. The last Democrat to carry one-third of the county's vote was Michael Dukakis in 1988 during an election severely affected by a major drought.

• Irwin Gunsalus (1912–2008), biochemist, was born in Sully County.

• National Register of Historic Places listings in Sully County, South Dakota