Western Pennsylvania
A map of counties in the western half of the Commonwealth.
Although not designated by the Commonwealth as an official region, Western Pennsylvania (“PA”) has retained a distinct identity because of its topographical separation from the East by the Appalachian Mountains.
Western PA encompasses the western third of the state, with Pittsburgh as the region’s principal city. Pittsburgh is a metropolitan area of about 2.4 million people, serving as Western PA’s economic and cultural center. Other metropolitan centers include Erie, Altoona, and Johnstown.
The largest rivers in this area are the Allegheny River, flowing southward, and the Monongahela flowing northward, meeting in Downtown Pittsburgh to join the Ohio River, which flows southwestward to the Mississippi River.