COUNTY · OH
Union County, Ohio
Union County is a county in Ohio with FIPS code 39159 and an estimated population of 69,637 (Census 2023), 36th largest of 88 in the state.
County facts
- Name
- Union County
- State
- Ohio
- Type
- county
- FIPS code
- 39159
- State FIPS
- 39
- Population (2023)
- 69,637
- Change since 2020
- +10.4%
- State rank
- 36 of 88
Population is the Census Bureau’s Vintage 2023 estimate.
Questions
What is the FIPS code for Union County?
Union County, Ohio has the five-digit FIPS code 39159: 39 for the state and 159 for the county.
What state is Union County in?
Union County is in Ohio.
How do I know if an address is in this county?
Use the address lookup. ZIP codes and city names can cross county lines, so an address is the reliable check.
Sources: U.S. Census Bureau geographic reference files; Census Bureau Population Estimates, Vintage 2023. Last reviewed 2026-10-27.