a city and port in SE Pennsylvania, at the confluence of the Delaware and Schuylkill Rivers: the fourth largest city in the US; founded by Quakers in 1682; cultural and financial centre of the American colonies and the federal capital (1790–1800); scene of the Continental Congresses (1774–83) and the signing of the Declaration of Independence (1776). Pop: 1 479 339 (2003 est)