Pennsylvania is a U.S. state located in the Northeastern and Mid-Atlantic regions of the United States. It is bordered by Delaware to the southeast, Maryland to the south, West Virginia to the southwest, Ohio to the west, Lake Erie and the Canadian province of Ontario to the northwest, New York to the north, and New Jersey to the east. The Appalachian Mountains run through the middle of the state. Pennsylvania is the 33rd-largest state by area and the 5th-most populous of the 50 United States. It is the 9th-most densely populated of the 50 states. The state capital is Harrisburg but the largest city is Philadelphia.