Pennsylvania, 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.
Pennsylvania is the 33rd largest, the 6th most populous, and the 9th most densely populated of the 50 United States. The state's five most populous cities are Philadelphia (1,560,297), Pittsburgh (305,801), Allentown (118,577), Erie (100,671), and Reading (89,893). The state capital is Harrisburg. Pennsylvania has 51 miles (82 km) of coastline along Lake Erie and 57 miles (92 km) of shoreline along the Delaware Estuary.
The state is one of the 13 original founding states of the United States; it was originally founded in 1681 as a result of a royal land grant to William Penn, the son of the state's namesake. It was the second state to ratify the United States Constitution on December 12, 1787. Independence Hall, where the United States Declaration of Independence and United States Constitution were drafted, is located in the state. During the American Civil War, the Battle of Gettysburg was fought in this state. More: en.wikipedia.org.