Philadelphia is the largest city in the Commonwealth of Pennsylvania, the fifth-most-populous city in the United States, and the core of the sixth-largest metropolitan area in the country. Located in the Northeastern United States at the confluence of the Delaware and Schuylkill rivers, Philadelphia is the economic and cultural center of the Delaware Valley. The population of the city — Pennsylvania’s only consolidated city-county — was measured at 1,526,006 in 2010 and estimated at 1,553,165 in 2013, according to the United States Census Bureau. The five Pennsylvania counties nearest Philadelphia have a total population of 4,008,994, while its Metropolitan Statistical Area, which includes parts of four states, is home to more than 6 million people. Popular nicknames for Philadelphia are Philly and The City of Brotherly Love.