High Quality Content by WIKIPEDIA articles! Interstate 81 is an 854.89-mile (1,375.81 km) long north–south Interstate Highway, stretching from Dandridge, Tennessee to Fisher`s Landing, New York at the United States/Canadian border. In the state of Pennsylvania, I-81 runs for 232.63 miles (374.38 km) from the Maryland state line near Chambersburg to the New York state line near Hallstead and is called the American Legion Memorial Highway.