The Commonwealth of Pennsylvania is divided into seven distinct geographic numbering plan areas in the North American Numbering Plan, and served by a total of fifteen area codes. All NPAs have at least two area codes, but the large metro area of Philadelphia has three, as well as the large region surrounding it in the southeast of the state.
Interactive map of the numbering plan areas of the Commonwealth of Pennsylvania (blue).
In 1947, the American Telephone and Telegraph Company divided Pennsylvania into four numbering plan areas and assigned one distinct area code to each. Since 1995, several relief actions in form of area code splits and overlays have expanded the number of area codes. As a result, all numbering plan areas are overlay complexes and ten-digit dialing is mandatory statewide.
Western Pennsylvania outside Pittsburgh and Allegheny County (except for outermost areas, such as Wexford, Gibsonia, Tarentum, parts of Monroeville, and parts of southern AC); completely surrounds 412
