Union
- County:
- Moody County
- County Seat:
- No
- Area (mi²):
- 22.424
- State:
- South Dakota
Union is located in Moody County, South Dakota. Union has a 2025 population of 87 . Union is currently growing at a rate of 3.57% annually and its population has increased by 8.75% since the most recent census, which recorded a population of 80 in 2020.
The median age in Union is 29.4 years: 0 years for males, and 0 years for females. For every 100 females there are 142.9 males.