Western Pennsylvania consists of the western third of the state of Pennsylvania

Pennsylvania

The Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...

 in the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

. Pittsburgh is the largest city in the region, with a metropolitan area

Metropolitan area

The term metropolitan area refers to a region consisting of a densely populated urban core and its less-populated surrounding territories, sharing industry, infrastructure, and housing. A metropolitan area usually encompasses multiple jurisdictions and municipalities: neighborhoods, townships,...

 population of about 2.4 million people, and serves as its economic and cultural center. Erie

Erie, Pennsylvania

Erie is a city located in northwestern Pennsylvania in the United States. Named for the lake and the Native American tribe that resided along its southern shore, Erie is the state's fourth-largest city , with a population of 102,000...

, Altoona

Altoona, Pennsylvania

-History:A major railroad town, Altoona was founded by the Pennsylvania Railroad in 1849 as the site for a shop complex. Altoona was incorporated as a borough on February 6, 1854, and as a city under legislation approved on April 3, 1867, and February 8, 1868...

, and Johnstown

Johnstown, Pennsylvania

Johnstown is a city in Cambria County, Pennsylvania, United States, west-southwest of Altoona, Pennsylvania and east of Pittsburgh. The population was 20,978 at the 2010 census. It is the principal city of the Johnstown, Pennsylvania, Metropolitan Statistical Area, which includes Cambria County...

 are its other large urban centers. As of the 2000 census, the total population of Western Pennsylvania was 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 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

Appalachian Mountains

The Appalachian Mountains #Whether the stressed vowel is or ,#Whether the "ch" is pronounced as a fricative or an affricate , and#Whether the final vowel is the monophthong or the diphthong .), often called the Appalachians, are a system of mountains in eastern North America. The Appalachians...

, which characterize so much of the western region.