Harrisburg is the capital of the United States Commonwealth of Pennsylvania. As of the 2010 census, the city had a population of 49,528, making it the ninth largest city in Pennsylvania. Harrisburg is also the county seat of Dauphin County and lies on the east bank of the Susquehanna River, 105 miles (169 km) west-northwest of Philadelphia.
The Harrisburg-Carlisle Metropolitan Statistical Area, which includes Dauphin, Cumberland, and Perry counties, had a population of 509,074 in 2000. A July 1, 2007 estimate placed the population at 528,892, making it the fifth largest Metropolitan Statistical Area in Pennsylvania after Philadelphia, Pittsburgh, Allentown–Bethlehem–Easton (the Lehigh Valley), and Scranton–Wilkes Barre. The Harrisburg-Carlisle-Lebanon Combined Statistical Area, including both the Harrisburg-Carlisle and Lebanon Metropolitan Statistical Areas, had an estimated population of 656,781 in 2007 and was the fourth-most populous metropolitan area in the state.
Harrisburg played a notable role in American history during the Westward Migration, the American Civil War, and the Industrial Revolution. During part of the 19th century, the building of the Pennsylvania Canal and later the Pennsylvania Railroad allowed Harrisburg to become one of the most industrialized cities in the Northeastern United States. The U.S. Navy ship USS Harrisburg, which served from 1918 to 1919 at the end of World War I, was named in honor of the city.