11 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Lewistown | 1 | 6,267 | 5,971 | 0.95% | 1,095 | 5.72 | City |
| Lewistown Heights | 2 | 506 | 312 | 1.4% | 215 | 2.36 | CDP |
| Denton | 3 | 214 | 208 | 0.47% | 300 | 0.71 | Town |
| Moore | 4 | 206 | 195 | 0.98% | 705 | 0.29 | Town |
| Roy | 5 | 177 | 120 | 2.91% | 52 | 3.40 | CDP |
| Winifred | 6 | 176 | 170 | 0.57% | 336 | 0.52 | Town |
| Grass Range | 7 | 117 | 112 | 0.86% | 836 | 0.14 | Town |
| Fords Creek Colony | 8 | 66 | 43 | 6.45% | 379 | 0.17 | CDP |
| Ayers Ranch Colony | 9 | 49 | 66 | 6.52% | 111 | 0.44 | CDP |
| King Ranch Colony | 10 | 24 | 69 | 9.09% | 22 | 1.11 | CDP |
| Danvers | 11 | 11 | 10 | 10% | 41 | 0.27 | CDP |
Lewistown is the largest city in Fergus County, with a population of 6,267.
Danvers is the smallest city in Fergus County.
There are 11 cities in Fergus County, Montana.