Philadelphia, often called Philly, is the largest city in the Commonwealth of Pennsylvania, the sixth-largest city in the U.S., the second-largest city in both the Northeast megalopolis and Mid-Atlantic regions after New York City. Since 1854, the city has been coextensive with Philadelphia County, the most populous county in Pennsylvania and the urban core of the Delaware Valley, the nation’s seventh-largest and one of world’s largest metropolitan regions, with 6.245 million residents as of 2020. The city’s population at the 2020 census was 1,603,797, and over 56 million people live within 250 mi (400 km) of Philadelphia. Wikipedia