United States Government--postal Service, Postal Shirleysburg Office Mount Union, PA 17066 Phone : (814) 447-5539 Business Category Government Offices-Federal Government Offices & Public Schools Post Office - Shirleysburg 17084 Croghan Pike Shirleysburg, PA 17260 Phone : (814) 447-5539 Business Category Post Offices Toll-Free           (800) ASK-USPS