Pennsylvania, officially the Commonwealth of Pennsylvania, is a state spanning the Mid-Atlantic, Northeastern, Appalachian, and Great Lakes regions of the United States. It borders Delaware to its southeast, Maryland to its south, West Virginia to its southwest, Ohio and the Ohio River to its west, Lake Erie and New York to its north, the Delaware River and New Jersey to its east, and the Canadian province of Ontario to its northwest via Lake Erie. Pennsylvania's most populous city is Philadelphia. The state capital is Harrisburg. Among all states, Pennsylvania is the fifth-most populous with over 13 million residents as of the 2020 United States census, the ninth-highest by population density, and the 33rd-largest by land area. The largest metropolitan statistical area is the southeastern Philadelphia metropolitan area, centered on Philadelphia, the state's most populous and nation's sixth-most populous city. The second-largest metropolitan area, Greater Pittsburgh, is centered in and around Pittsburgh, the state's second-largest city.