Post Offices List in Powder River County, Montana:
| Biddle Post Office | 218 S State Highway 59, Biddle, MT 59314 |
| Broadus Post Office | 202 N Lincoln Ave, Broadus, MT 59317 |
| Otter Post Office | 268 Otter Creek Rd, Otter, MT 59062 |
| Volborg Post Office | 2708 Highway 59, Volborg, MT 59351 |