Pennsylvania ( PEN-sil-VAY-nee-ə; Pennsylvania German: Pennsilfaani), officially the Commonwealth of Pennsylvania, is a state spanning the Mid-Atlantic, Northeastern, Appalachian, and Great Lakes regions of the United States. Pennsylvania borders Delaware to its southeast, Maryland to its south, West Virginia to its southwest, Ohio to its west, Lake Erie and the Canadian province of Ontario to its northwest, New York to its north, and the Delaware River and New Jersey to its east.
Pennsylvania is the fifth-most populous state in the United States, with over 13 million residents as of the 2020 United States census. The state is the 33rd-largest by area and has the ninth-highest population density among all states. The largest metropolitan statistical area (MSA) is the southeastern Delaware Valley, which includes and surrounds Philadelphia, the state's largest and nation's sixth-most populous city.