Post Offices List in Boone County, Illinois:
| Belvidere Post Office | 1800 Doc Wolf Dr, Belvidere, IL 61008 |
| Caledonia Post Office | 2201 Il Route 173, Caledonia, IL 61011 |
| Capron Post Office | 120 W Main St, Capron, IL 61012 |
| Garden Prairie Post Office | 6820 Pleasant St, Garden Prairie, IL 61038 |
| Poplar Grove Post Office | 105 E Britnie Dr, Poplar Grove, IL 61065 |