Post Office - Alton 1022 3rd Ave Alton, IA 51003 Phone : (712) 756-8815 Post Office - Alton Business Category Post Offices Toll-Free           (800) ASK-USPS United States Government--post Office 217 10th St Alton, IA 51003 Phone : (712) 756-8815 United States Government--post Office Business Category Government Offices-Federal Post Offices Government Offices & Public Schools