Western Pennsylvania is a region in the Commonwealth of Pennsylvania encompassing the western third of the state. Pittsburgh is the region's principal city, with a metropolitan area population of about 2.4 million people, and serves as its economic and cultural center. Erie, Altoona, and Johnstown are its other metropolitan centers. As of the 2010 census, Western Pennsylvania's total population is nearly 4 million. Although the Commonwealth does not designate Western Pennsylvania as an official region, since colonial times it has retained a distinct identity not only because of its geographical distance from Philadelphia, the beginning of Pennsylvania settlement, but especially because of its topographical separation from the east by virtue of the Appalachian Mountains, which characterize much of the western region. The strong cultural identity of Western Pennsylvania is reinforced by the state supreme court holding sessions in Pittsburgh, in addition to Harrisburg and Philadelphia. Counties Since at least the early twentieth century, scholarly books such as Guidebook to Historic Western Pennsylvania, published by the University of Pittsburgh Press (1938), formally define the region as the twenty-six counties west of the Appalachian divide, a meridian from the north at McKean County down and along its eastern border and ending in the south at Bedford County. In alphabetical order those counties are: Allegheny Armstrong Beaver Bedford Blair Butler Cambria Cameron Clarion Clearfield Crawford Elk Erie Fayette Forest Greene Indiana Jefferson Lawrence McKean Mercer Somerset Venango Warren Washington Westmoreland Description Long recognized as a powerhouse of American industry, Western Pennsylvania is a large geophysical and socio-economic entity. It encompasses that portion of the state to the west of the Appalachian divide and included within the Mississippi drainage system of rivers. The largest rivers in this area are the Allegheny River, which flows southward from the New York border, and the Monongahela River, which flows northward from West Virginia. These two rivers meet in Downtown Pittsburgh and join to form the Ohio River, which from that point flows an additional southwest to the Mississippi River. The juncture of the Allegheny and Monongahela was historically regarded as strategic and the gateway to the interior of the continent from the east. At various times this juncture has been called the Forks of the Ohio, Fort Duquesne, Fort Pitt, the Golden Triangle, and today, at its apex, Point State Park. Incredibly, after several decades of border war and 150 years of high-rent city-center urbanization, the original