Pennsylvania (Pennsylvania German: Pennsilfaani), officially the Commonwealth of Pennsylvania, is a U.S. state located in the North and Mid-Atlantic regions of the United States and the Great Lakes region. The Appalachian Mountains run through its middle. The state borders Delaware to the southeast, Maryland to the south, West Virginia to the southwest, Ohio to the west, Lake Erie and Ontario, Canada to the northwest, New York to the north, and New Jersey to the east.