COUNTY · PA
Allegheny County, Pennsylvania
Allegheny County is a county in Pennsylvania with FIPS code 42003 and an estimated population of 1,224,825 (Census 2023), 2nd largest of 67 in the state.
County facts
- Name
- Allegheny County
- State
- Pennsylvania
- Type
- county
- FIPS code
- 42003
- State FIPS
- 42
- Population (2023)
- 1,224,825
- Change since 2020
- -2.0%
- State rank
- 2 of 67
Population is the Census Bureau’s Vintage 2023 estimate.
Major cities in Allegheny County
Other counties in Pennsylvania
Questions
What is the FIPS code for Allegheny County?
Allegheny County, Pennsylvania has the five-digit FIPS code 42003: 42 for the state and 003 for the county.
What state is Allegheny County in?
Allegheny 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.