| Zip or zip prefix | Area | ||
|---|---|---|---|
| 594 | Great Falls | ||
| 596 | Helena | ||
| 597 | Bozeman / Butte | ||
| 598 | Missoula | ||
| 59828 | Bitterroot | ||
| 59840 | Bitterroot | ||
| 59860 | Mission Valley | ||
| 59864 | Mission Valley | ||
| 59865 | Mission Valley | ||
| 59870 | Bitterroot | ||
| 59875 | Bitterroot | ||
| 599 | Flathead Valley | ||
| 59917 | Eureka / Tobacco Valley | ||
| 59923 | Libby / Troy | ||
| 59935 | Libby / Troy |