Scotch-Irish Settlements in Pennsylvania:
A distinct section, occupied predominantly by Scotch-Irish, was formed in Western Pennsylvania, which was to have an important effect on the internal politics of that province. HERBERT L. OSGOOD
AFTER REACHING the foothills of the Alleghenies, the westward movement of the Scotch-Irish in Pennsylvania was checked for a time by the mountain barrier, by the remoteness and inaccessibility of the trans-Allegheny region, by the Indian wars, by the uncertainty of land titles caused by the boundary dispute between Pennsylvania and Virginia, and by the failure of the Penns to extinguish the Indian claims to this territory prior to 1768. Nevertheless, despite the hazards involved, there were not wanting a few daring souls who located west of the mountains at an early date. During the French and Indian War and Pontiac's War the first comers were forced to flee for their lives to the more settled parts of the province, if indeed they escaped massacre at the hands of the savages. With the return of peace, however, and the Land Purchase of 1768, the occupation of the trans-Allegheny region began in earnest.
Southwestern Pennsylvania, in the restricted sense in which the term was long understood, embraced the present counties of Somerset, Westmoreland, Fayette, Allegheny, Washington, and