Union County's 2026 population is estimated at 17,834, reflecting a 1.23% growth rate over the past year (World Population Review estimate based on U.S. Census Bureau data). Union County is the 12th largest county in South Dakota. The 2010 population was 14,488 and has grown 23.09% since 2010.
Data after 2023 is projected based on recent change
Overall: 41.5 years
Female: 42.8 years
Male: 39.7 years
There are 12,973 adults, (3,328 of whom are seniors) in Union County.
Female: 8,269 (48.4%)
Male: 8,812 (51.6%)
The racial composition of Union County includes 89.97% White, and smaller percentages for Asian, Native American, Black or African American, other race, Native Hawaiian or Pacific Islander and multiracial populations.
| Race | Population ↓ | Percentage (of total) |
|---|---|---|
| White | 15,367 | 89.97% |
| Two or more races | 1,054 | 6.17% |
| Asian | 190 | 1.11% |
| Native American | 167 | 0.98% |
| Black or African American | 160 | 0.94% |
| Other race | 125 | 0.73% |
| Native Hawaiian or Pacific Islander | 18 | 0.11% |
Union County 's average per capita income is $59,260. Household income levels show a median of $89,636. The poverty rate stands at 6.21%.
| Name | Median ↓ | Mean |
|---|---|---|
| Married Families | $118,022 | - |
| Families | $109,958 | $153,155 |
| Households | $89,636 | $124,814 |
| Non Families | $46,990 | $59,606 |
Average Income
Median Household Income
Poverty Rate