Historically, settlement patterns have largely been blocked by the mountainous zones throughout the Eastern United States, known as the Appalachian Mountains. Further east along the mountains and valleys, however, is the vast majority of the population of the Commonwealth of Pennsylvania, with the largest city, Philadelphia, located within the region, as well as Allentown, Reading, Lancaster, York, Bethlehem, Easton, Chambersburg, Shippensburg, Carlisle, Harrisburg, and numerous other communities with a significant historical significance in every case.
