Us Government--postal Service, Monroe Center Monroe Center, IL 61052 Phone : (815) 393-4345 Business Category Government Offices-Federal Government Offices & Public Schools Post Office - Monroe Center 200 Main St Monroe Center, IL 61052 Phone : (815) 393-4345 Business Category Post Offices Toll-Free           (800) ASK-USPS Fax           (815) 393-3126