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.Contrasted with its 1981 status as the second most distressed city in the nation, Harrisburg has undergone a dramatic economic change, with nearly $3 billion in new investment now realized. The U.S. Navy ship USS Harrisburg, which served from 1918-19 at the end of World War I, is named in honor of the city.
The Pennsylvania Farm Show, the largest 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 the annual "Auto Show," a large static display of new as well as classic cars, which is renowned nation-wide. Harrisburg is also known for the infamous Three Mile Island accident, which occurred in nearby Middletown.