Harrisburg, city (1990 pop. 52,376), state capital and seat of Dauphin co., SE Pa., on the Susquehanna River; settled c.1710 by John Harris, who established a trading post and operated a ferry there; inc. 1791. It is a commercial, wholesale, administrative, and transportation center. Manufactures include metal products, transportation equipment, processed foods, machinery, electrical and electronic equipment, building materials, and steel. Harrisburg became the state capital in 1812 and grew as an inland transportation center with the opening of the Pennsylvania Canal in 1827 and the arrival of the railroad in 1836.
The sprawling Italian Renaissance state capitol (completed 1906) has a 272-ft (83-m) dome modeled after St. Peter's in Rome. Other notable structures are the education building, which contains the state library; the State Museum of Pennsylvania; the National Civil War Museum; the William Penn Memorial Museum; the John Harris Mansion (1766), headquarters of the county historical society; and the Soldiers' and Sailors' Memorial Bridge. A medical center and the Pennsylvania State Univ. Center are in Harrisburg. The city has numerous parks. To the south is the large Three Mile Island facility, site of a nuclear accident in 1979. The New Cumberland Army Depot, the U.S. Army War College, and the U.S. Naval Supply Depot are also nearby.