Westmoreland County, Pennsylvania is located west of a mountain range that runs for about how many miles?
Westmoreland County, Pennsylvania:  Cut from Lancaster, Northumberland, and later Bedford Counties, Westmoreland County was founded on February 26, 1773 and was the first county in the colony of Pennsylvania in which its entire territorial boundary was located west of the Allegheny Mountains. Allegheny Mountains:  The barrier range has a northeast–southwest orientation and runs for about 400 miles (640 km) from north-central Pennsylvania, through western Maryland and eastern West Virginia, to southwestern Virginia.
400