10 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Lockwood | 1 | 7,542 | 8,206 | 0.67% | 587 | 12.86 | CDP |
| Hardin | 2 | 3,643 | 3,807 | -0.9% | 1,225 | 2.97 | City |
| Crow Agency | 3 | 2,052 | 1,972 | 1.43% | 280 | 7.34 | CDP |
| Muddy | 4 | 672 | 604 | 0.6% | 23 | 28.63 | CDP |
| Pryor | 5 | 632 | 579 | 0.16% | 16 | 39.80 | CDP |
| Lodge Grass | 6 | 423 | 437 | -0.7% | 1,640 | 0.26 | Town |
| Busby | 7 | 406 | 586 | -5.36% | 28 | 14.32 | CDP |
| Wyola | 8 | 274 | 199 | 1.48% | 41 | 6.73 | CDP |
| Fort Smith | 9 | 104 | 160 | -2.8% | 75 | 1.38 | CDP |
| St. Xavier | 10 | 98 | 184 | 7.69% | 18 | 5.60 | CDP |
Lockwood is the largest city in Big Horn County, with a population of 7,542.
St. Xavier is the smallest city in Big Horn County.
There are 10 cities in Big Horn County, Montana.