Post Offices List in Union County, Illinois:
| Alto Pass Post Office | 85 N Elm St, Alto Pass, IL 62905 |
| Anna Post Office | 201 N Main St, Anna, IL 62906 |
| Cobden Post Office | 113 S Appleknocker St, Cobden, IL 62920 |
| Dongola Post Office | 106 E Cross St, Dongola, IL 62926 |
| Jonesboro Post Office | 103 W Broad St, Jonesboro, IL 62952 |
| Millcreek Post Office | 60 Walnut St, Millcreek, IL 62961 |
| Wolf Lake Post Office | 4675 N State Route 3, Wolf Lake, IL 62998 |