40.01, -75.13
Philadelphia County is the most populous county in Pennsylvania and the 24th-most populous county in the nation. As of the 2020 census, the county had a population of 1,603,797. Its county seat is Philadelphia, the nation's sixth-largest city.
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, also known as the Delaware Valley), located along the lower Delaware and Schuylkill Rivers, within the Northeast megalopolis.
Philadelphia County is the economic and cultural anchor of the Delaware Valley, the ninth-largest combined statistical area in the nation with an estimated population of 7,381,187 as of 2022.