United States Government--postal Service, Harrisburg Stations & Branches, Offices, Mt Gretna Rr 117 Mount Gretna, PA 17064 Phone : (717) 964-3804 Business Category Government Offices & Public Schools Post Office - Mount Gretna 101 Princeton Ave Mount Gretna, PA 17064 Phone : (717) 964-3804 Business Category Post Offices Toll-Free           (800) ASK-USPS U S Government--postal Service, Mt Gretna Rr 117 Mount Gretna, PA 17064 Phone : (717) 964-3804 Business Category Government Offices-Federal Government Offices & Public Schools United States Government--army Corps Of Engineers 285 18th St New Cumberland, PA 17070 Phone : (717) 964-3804 Business Category Government Offices-Federal Government Offices & Public Schools