Harrisburg is the capital of the Commonwealth of Pennsylvania, in the United States of America. As of the 2000 census, the city had a population of 48,950, making it the ninth largest city in Pennsylvania, after Philadelphia, Pittsburgh, Allentown, Erie, Reading, Scranton, Bethlehem and Lancaster. Harrisburg is 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, 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. 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. In the mid-to-late 20th century, the city's economic fortunes have fluctuated with its major industries consisting of government, heavy manufacturing including the production of steel, agriculture (the greater Harrisburg area is at the heart of the fertile Pennsylvania Dutch Country), and food services (nearby Hershey is home of the chocolate maker, located just 10 miles east of Harrisburg). In 1981, following contractions in the steel and dairy industries, Harrisburg was declared the second most distressed city in the nation. The city subsequently experienced a resurgence under its former mayor Stephen R. Reed, with nearly $3 billion in new investment realized during his lengthy tenure. The Pennsylvania Farm Show, the largest free indoor agriculture exposition in the United States, was first held in Harrisburg in 1917 and has been held there every January since then. Harrisburg also hosts an annual outdoor sports show, the largest of its kind in North America, as well as an auto show, which features a large static display of new as well as classic cars and is renowned nation-wide. Harrisburg is also known for the infamous Three Mile Island accident, which occurred in 1979 in nearby Middletown.