Post Office - Allendale 101 Main St Allendale, MO 64420 Phone : (660) 786-2293 Post Office - Allendale Business Category Post Offices Toll-Free           (800) ASK-USPS United States Government--post Office, Allendale Allendale, MO 64420 Phone : (660) 786-2293 Business Category Government Offices-Federal Post Offices Government Offices & Public Schools