Post Office - Karns City 108 Petrolia St Karns City, PA 16041 Phone : (724) 756-3150 Business Category Government Offices-Federal Post Offices Services Miscellaneous Government Offices & Public Schools Toll-Free           (800) ASK-USPS U.s. Government--u.s. Postal Service, Karns City Ofc 108 Petrolia St Petrolia, PA 16050 Phone : (724) 756-3150 Business Category Government Offices-Federal Government Offices & Public Schools