4 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Miles City | 1 | 8,422 | 8,348 | 0.18% | 2,505 | 3 | City |
| Miles City | 2 | 8,422 | 8,346 | 0.18% | 2,505 | 3 | City |
| Ismay | 3 | 21 | 21 | 0% | 50 | 0 | Town |
| Ismay | 4 | 21 | 21 | 0% | 50 | 0 | Town |
Miles City is the largest city in Custer County, with a population of 8,422.
Ismay is the smallest city in Custer County, with a population of 21.
There are 4 cities in Custer County, Montana.