15642 is a valid ZIP Code for , and areas in Westmoreland County . However, 156421 is a 6-digit number and does not exist as a standard 5-digit United States ZIP Code.

Approximately 33,000 residents as of recent census estimates.

A mix of historic borough residential areas and suburban developments.

Retail, healthcare, and light manufacturing, with many residents commuting to Pittsburgh for work. Potential Alternatives If "156421" was a typo, you might be looking for: 15642 : Irwin, PA (the most likely intent). 16421 : A ZIP Code in Erie County, PA .

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