Harrisburg (, Pennsylvania German: Harrisbarrig) is the capital city of the Commonwealth of Pennsylvania, United States, and the seat of Dauphin County. With a population of 50,135 as of 2021, Harrisburg is the ninth-most populous city in Pennsylvania. Harrisburg is situated on the east bank of the Susquehanna River. It is the larger principal city of the Harrisburg–Carlisle metropolitan statistical area, also known as the Susquehanna Valley, which had a population of 591,712 as of 2020, making it the fourth-most populous metropolitan area in Pennsylvania after the Philadelphia, Pittsburgh, and Lehigh Valley metropolitan areas. Harrisburg played a 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 develop into one of the most industrialized cities in the Northeastern United States. In the mid- to late 20th century, the city's economic fortunes fluctuated with its major industries consisting of government, heavy manufacturing, agriculture, and food services. These economic fluctuations contributed to Harrisburg experiencing a decline of nearly half its population between 1950 and 2000. The Pennsylvania Farm Show, the largest indoor agriculture exposition in the U.S., was first held in Harrisburg in 1917 and has been held there every early to mid-January since. The city also hosts the annual Great American Outdoor Show, the largest of its kind in the world, among many other events. Harrisburg experienced the Three Mile Island accident on March 28, 1979, in nearby Middletown. In 2010, Forbes rated Harrisburg as the second-best place in the U.S. to raise a family. Despite the city's past financial troubles, in 2010 The Daily Beast website ranked 20 metropolitan areas across the country as being recession-proof, and the Harrisburg region was ranked seventh. The financial stability of the region is in part due to the high concentration of state and federal government agencies. Harrisburg is located 83 miles (134 km) miles southwest of Allentown, the state's third-largest city, and 107 miles (172 km) northwest of Philadelphia, its largest city.