Philadelphia County, Pennsylvania
Philadelphia County is the most populous of the 67 counties of Pennsylvania and the 24th-most populous county in the nation. As of the 2020 census, the county had a population of 1,603,797. It is coextensive with Philadelphia, the nation's sixth-largest city. The county is part of the Southeast region of the commonwealth.
Philadelphia County is one of the three original counties, along with Chester and Bucks counties, founded by William Penn in November 1682. Since 1854, the county has been coextensive with the City of Philadelphia, which is also its county seat. Philadelphia County is the core county in the Philadelphia-Camden-Wilmington Combined Statistical Area (PA-NJ-DE-MD, located along the lower Delaware and Schuylkill Rivers, within the Northeast megalopolis).
Philadelphia County is the Delaware Valley's economic and cultural anchor and the ninth-largest combined statistical area in the nation with an estimated population of 7,493,171 as of 2025.