7 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Roundup | 1 | 2,084 | 1,743 | 3.32% | 1,612 | 1 | City |
| Roundup | 2 | 2,084 | 1,748 | 3.32% | 1,612 | 1 | City |
| Klein | 3 | 283 | 156 | 2.91% | 22 | 13 | CDP |
| Melstone | 4 | 151 | 129 | 2.72% | 246 | 1 | Town |
| Melstone | 5 | 151 | 129 | 2.72% | 246 | 1 | Town |
| Camp Three | 6 | 150 | 150 | -1.32% | 34 | 4 | CDP |
| Musselshell | 7 | 41 | 23 | 7.89% | 16 | 3 | CDP |
Roundup is the largest city in Musselshell County, with a population of 2,084.
Musselshell is the smallest city in Musselshell County, with a population of 41.
There are 7 cities in Musselshell County, Montana.