
Mercer County
- State:
- Pennsylvania
- County Seat:
- Mercer
Mercer County's estimated 2025 population is 107,235 with a growth rate of -0.59% in the past year according to the most recent United States census data. Mercer County is the 31st largest county in Pennsylvania. The 2010 population was 116,607 and has seen a growth of -8.04% since that time.