Post Office - Hartshorn 6041 State Route Kk Hartshorn, MO 65479 Phone : (417) 932-4443 Post Office - Hartshorn Business Category Post Offices Toll-Free           (800) ASK-USPS U S Government--post Offices, Hartshorn 6041 Highway Kk Summersville, MO 65571 Phone : (417) 932-4443 Business Category Government Offices-Federal Post Offices Government Offices & Public Schools