About Philadelphia

Philadelphia ( (listen) FILL-ah-dəl-FEE-ah), often called Philly, is the largest city in the Commonwealth of Pennsylvania and the second-largest city in both the Northeast megalopolis and Mid-Atlantic regions after New York City. It is one of the most historically significant cities in the United States and served as the nation's capital until 1800. Philadelphia is the nation's sixth-largest city with a population of 1,603,797 as of the 2020 census. 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 the world's largest metropolitan regions with 6.245 million residents. Philadelphia is known for its extensive contributions to American history, especially the American Revolution, and for its contemporary influence in business and industry, culture, sports, and music.Philadelphia was founded in 1682 by William Penn, an English Quaker and advocate of religious freedom.