Union
- County:
- Miami County
- County Seat:
- No
- Area (mi²):
- 8.489
- State:
- Ohio
Union is a city located in Miami County, Ohio. Union has a 2026 population of 7,076. Union is currently growing at a rate of 1.07% annually and its population has increased by 2.55% since the most recent census, which recorded a population of 6,900 in 2020.