
Union County
- State:
- Pennsylvania
- County Seat:
- Lewisburg
Union County's estimated 2025 population is 40,746 with a growth rate of -1.57% in the past year according to the most recent United States census data. Union County is the 50th largest county in Pennsylvania. The 2010 population was 45,005 and has seen a growth of -9.46% since that time.