How many people live in Union County, SD?
Updated Apr. 6, 2026Refreshed annually
In 2024, there were about 17,400 people living in Union County, SD. That makes Union County the 13th-most populous county in South Dakota. It is home to 1.9% of people living in the state.
17.4K
population of Union County, SD (2024)
1.9%
County share of the South Dakota population (2024)
About 17,400 people lived in Union County, SD in 2024.
Population estimates, 2000–2024
What are Union County, SD’s age demographics?
About 3,500 Union County residents are aged 65 and older in 2024. That represents 20.1% of its population. For comparison, the age group represents 18.9% of South Dakota’s population and 18% in the US overall.
Another 4,100 Union County, SD residents, or 23.6% of the population, were children under 18. For comparison, the age group represents 24% of South Dakota’s population and 21.6% in the US overall.
A lower share of Union County, SD's population is aged 25–44 than the US as a whole.
Population estimates by age group, (2024)
What are Union County, SD’s racial and ethnic demographics?
Non-Hispanic white residents make up 88.8% of the Union County, SD population, higher than the national share of 57.5%. Union County, SD also has a larger share of people identifying as non-Hispanic American Indian and Alaska Native (0.84%) than the US overall (0.72%).
In contrast, Union County’s Hispanic population accounts for 5.5%, below the 20% nationwide, and the non-Hispanic Black or African American population makes up 1.5% of the county, compared with 12.6% nationally.
Racial and ethnic make up differ based on location. These figures reflect how people identified their race alone (not in combination with other races), and separate out Hispanic or Latino ethnicity, following Census reporting standards.
Union County, SD has a higher share of a non-Hispanic white population than South Dakota as a whole.
Population estimates by race and ethnicity, (2024)
The largest city or town in Union County, SD is Big Sioux with about 5,100 residents in 2024.
Cities and towns in Union County, SD ranked by population
Population (2024), includes only portions within county
| City or town | Population | |
|---|---|---|
| 1. | Big Sioux | 5,145 |
| 2. | North Sioux City | 3,059 |
| 3. | Elk Point | 2,074 |
| 4. | Beresford (pt.) | 1,728 |
| 5. | Jefferson | 1,209 |
| 6. | Alcester | 772 |
| 7. | Jefferson | 449 |
| 8. | Civil Bend | 344 |
| 9. | Alcester | 307 |
| 10. | Elk Point | 283 |
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Methodology
USAFacts standardizes data, in areas such as time and demographics, to make it easier to understand and compare.
The analysis was generated with the help of AI and reviewed by USAFacts for accuracy.
Page sources
USAFacts endeavors to share the most up-to-date information available. We sourced the data on this page directly from government agencies; however, the intervals at which agencies publish updated data vary.
