Post Office - Karnak 210 N 1st St Karnak, IL 62956 Phone : (618) 634-9355 Business Category Post Offices Toll-Free           (800) ASK-USPS United States Government--post Offices, Karnak Karnak, IL 62956 Phone : (618) 634-9355 Business Category Government Offices-Federal Post Offices Government Offices & Public Schools