Philadelphia is in the United States.
Philadelphia ( [ ˌfɪləˈdɛlfi.ə ] ) is the largest city in the Commonwealth of Pennsylvania and the sixth-most populous city in the United States , with an estimated population of 1,567,872 and more than 6 million in the seventh-largest metropolitan statistical area , . Philadelphia is the only World Heritage City in the United States . United States . The capital is Washington , D.C. , and the largest city is New York City ; nine other major metropolitan areas -- each with at least 4.5 million inhabitants and the largest having more than 13 million people -- are Los Angeles , Chicago , Dallas , Houston , Philadelphia , Miami , Atlanta , Boston , and San Francisco .