Area code 717 is a telephone area code which serves south central Pennsylvania, used in the Harrisburg-Lancaster-York metropolitan areas.717 was one of the original area codes established in 1947. It originally covered the eastern half of the state except for the Delaware and Lehigh valleys.he 717 area code was split on December 5, 1998, when the northern portion (centered on Scranton, Wilkes-Barre and Williamsport) became area code 570. As of May 2005, the subscriber number pool of the 717 area code was allocated by 52%, with 48% still unassigned.