Union County is a county in the U.S. state of South Dakota. As of the 2010 United States Census, the population was 14,399. Its county seat is Elk Point. Originally named Cole County, its name was changed to Union because of Civil War sentiment.
Union County lies on the SE corner of South Dakota. Its east boundary line abuts the west boundary line of the state of Iowa (across the Big Sioux River), and its south/southwest boundary line abuts the north boundary line of the state of Nebraska (across the Missouri River). The Brule Creek flows southeasterly across the central part of the county, discharging into Big Sioux. The county terrain consists of rolling hills, devoted to agriculture except around built-up areas. The terrain slopes to the south and east; its highest point is near its NW corner, at 1,509′ (460m) ASL. The county has a total area of 467 square miles (1,210 km), of which 461 square miles (1,190 km) is land and 6.6 square miles (17 km) (1.4%) is water. It is the fifth-smallest county in South Dakota by area.
As of the 2000 United States Census, there were 12,584 people, 4,927 households, and 3,517 families in the county. The population density was 27 people per square mile (11/km²). There were 5,345 housing units at an average density of 12 per square mile (4/km²). The racial makeup of the county was 96.85% White, 1.34% Asian, 0.37% Native American, 0.01% Pacific Islander, 0.33% Black or African American, 0.24% from other races, and 0.87% from two or more races. 1.26% of the population were Hispanic or Latino of any race.
There were 4,927 households out of which 34.80% had children under the age of 18 living with them, 62.00% were married couples living together, 6.30% had a female householder with no husband present, and 28.60% were non-families. 24.20% of all households were made up of individuals and 10.30% had someone living alone who was 65 years of age or older. The average household size was 2.53 and the average family size was 3.02.
The county population contained 27.00% under the age of 18, 7.30% from 18 to 24, 28.40% from 25 to 44, 23.70% from 45 to 64, and 13.50% who were 65 years of age or older. The median age was 37 years. For every 100 females, there were 99.20 males. For every 100 females age 18 and over, there were 98.30 males.
The median income for a household in the county was $44,790, and the median income for a family was $51,227. Males had a median income of $35,406 versus $23,440 for females. The per capita income for the county was $24,355. About 3.70% of families and 5.50% of the population were below the poverty line, including 4.90% of those under age 18 and 10.70% of those age 65 or over.
As of the 2010 United States Census, there were 14,399 people, 5,756 households, and 4,043 families in the county. The population density was 31.3 inhabitants per square mile (12.1/km). There were 6,280 housing units at an average density of 13.6 per square mile (5.3/km). The racial makeup of the county was 95.5% white, 0.9% Asian, 0.7% black or African American, 0.6% American Indian, 0.1% Pacific islander, 0.7% from other races, and 1.6% from two or more races. Those of Hispanic or Latino origin made up 2.1% of the population. In terms of ancestry, 42.0% were German, 18.2% were Norwegian, 17.7% were Irish, 7.9% were English, 6.8% were Swedish, and 3.7% were American.
Of the 5,756 households, 32.8% had children under the age of 18 living with them, 58.9% were married couples living together, 7.5% had a female householder with no husband present, 29.8% were non-families, and 25.1% of all households were made up of individuals. The average household size was 2.49 and the average family size was 2.98. The median age was 40.2 years.
The median income for a household in the county was $59,889 and the median income for a family was $71,308. Males had a median income of $42,702 versus $31,993 for females. The per capita income for the county was $33,783. About 3.9% of families and 4.9% of the population were below the poverty line, including 4.3% of those under age 18 and 10.5% of those age 65 or over.
Union County South Dakota neighborhoods include: Alcester, Baltic, Black Hawk, Box Elder, Brandon, Buffalo Ridge, Camp Crook, Canton, Caputa, Central City, Chancellor, Colton, Creighton, Crooks, Custer, Deadwood, Dell Rapids, Elkton, Ellsworth Afb, Garretson, Hartford, Hermosa, Hill City, Howes, Humboldt, Keystone, Lead, Ludlow, Montrose, Nemo, New Underwood, North Sioux City, Owanka, Parker, Quinn, Rapid City, Renner, Rowena, Saint Onge, Scenic, Sherman, Silver City, Sioux Falls, Spearfish, Sturgis, Valley Springs, Wall, Wanblee, Wasta, Whitewood