Philadelphia, colloquially referred to as Philly, is the most populous city in the U.S. state of Pennsylvania and the sixth-most populous city in the United States, with a population of 1,603,797 in the 2020 census. The city is the urban core of the larger Delaware Valley, also known as the Philadelphia metropolitan area, the nation's eighth-largest metropolitan area and seventh-largest combined statistical area with 6.245 million residents and 7.366 million residents, respectively.