Philadelphia, often called Philly, is the largest city in the Commonwealth of Pennsylvania, and the sixth-largest city in the U.S.; is centrally located as the second-largest city in the Northeast megalopolis; and is the 67th-largest city in the world. Since 1854, the city has had the same geographic boundaries as Philadelphia County, the most populous county in Pennsylvania and the urban core of the Delaware Valley, the nation's seventh-largest and world's 35th-largest metropolitan region, with 6.096 million residents as of 2020. The city's population as of the 2020 census was 1,603,797. Philadelphia was founded in 1682 by William Penn, an English Quaker. The city served as capital of the Pennsylvania Colony during the British colonial era. Philadelphia went on to play a historic and vital role in the 18th century as the central meeting place for the nation's founding fathers whose plans and actions in Philadelphia ultimately inspired and resulted in the American Revolution.