CITY · PA

What county is Philadelphia, PA in?

Philadelphia, PA is mostly in Philadelphia County. County FIPS code 42101, population 1,550,542 (2023 estimate).

County details

City: Philadelphia, Pennsylvania
Primary county: Philadelphia County
FIPS code: 42101
County population: 1,550,542

Some cities extend into more than one county. Philadelphia is placed in the county that contains its center. For a specific address, use the address lookup.

Questions

What county is Philadelphia in?

Philadelphia, PA is mostly in Philadelphia County.

What is the county seat of Philadelphia County?

County seats are not part of the data on this site. Check the county’s official website.

Can a city be in two counties?

Yes. Large cities such as Houston and Atlanta cross county lines. The address lookup shows the exact county for any street address.

Sources: U.S. Census Bureau geographic reference files; FCC Area API; Census Bureau Population Estimates, Vintage 2023. Last reviewed 2026-10-27.