11 cities
| City | County | 2025 Pop. ↓ |
|---|---|---|
| Orchard Mesa | Mesa County | 7,257 |
| Orchard City | Delta County | 3,317 |
| Olathe | Montrose County | 1,926 |
| Ordway | Crowley County | 1,086 |
| Ouray | Ouray County | 934 |
| Oak Creek | Routt County | 838 |
| Otis | Washington County | 526 |
| Olney Springs | Crowley County | 285 |
| Ovid | Sedgwick County | 261 |
| Ophir | San Miguel County | 186 |
| Orchard | Morgan County | 108 |