COUNTY · PA
Mercer County, Pennsylvania
Mercer County is a county in Pennsylvania with FIPS code 42085 and an estimated population of 108,503 (Census 2023), 30th largest of 67 in the state.
County facts
- Name
- Mercer County
- State
- Pennsylvania
- Type
- county
- FIPS code
- 42085
- State FIPS
- 42
- Population (2023)
- 108,503
- Change since 2020
- -1.9%
- State rank
- 30 of 67
Population is the Census Bureau’s Vintage 2023 estimate.
Questions
What is the FIPS code for Mercer County?
Mercer County, Pennsylvania has the five-digit FIPS code 42085: 42 for the state and 085 for the county.
What state is Mercer County in?
Mercer County is in Pennsylvania.
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.