| Name | What | Region | Country | Lat | Long | Elev ft. | Pop est |
|---|---|---|---|---|---|---|---|
| Oak Creek | city | Colorado | United States | 40.27 | -106.96 | 7549 | |
| Oak Grove | city | Colorado | United States | 38.46 | -107.93 | 5885 | |
| Oak Park | city | Colorado | United States | 39.84 | -105.12 | 5869 | |
| Oberon Acres | city | Colorado | United States | 39.84 | -105.12 | 5869 | |
| Occidental | city | Colorado | United States | 37.52 | -105.11 | 7706 | |
| Oehlmann Park | city | Colorado | United States | 39.52 | -105.26 | 8389 | |
| Offield Place | city | Colorado | United States | 40.99 | -108.66 | 6709 | |
| Ohio | city | Colorado | United States | 38.57 | -106.61 | 9228 | |
| Olathe | city | Colorado | United States | 38.60 | -107.98 | 5396 | |
| Old Fort Bent (historical) | city | Colorado | United States | 38.04 | -103.43 | 4189 | |
| Old Fort Lyons | city | Colorado | United States | 38.10 | -102.77 | 3697 | |
| Old Fort Vasquez (historical) | city | Colorado | United States | 40.19 | -104.82 | 5029 | |
| Old Homestead | city | Colorado | United States | 40.44 | -106.14 | 8799 | |
| Old Mountain View (historical) | city | Colorado | United States | 38.83 | -104.99 | 9583 | |
| Old Roach | city | Colorado | United States | 40.92 | -106.12 | 9399 | |
| Old Towne | city | Colorado | United States | 39.71 | -104.85 | 5869 | |
| Old Wells | city | Colorado | United States | 38.90 | -102.33 | 4189 | |
| Olinger Gardens | city | Colorado | United States | 39.76 | -105.06 | 5383 | |
| Olney Springs | city | Colorado | United States | 38.17 | -103.94 | 4343 | |
| Olympus Heights | city | Colorado | United States | 40.38 | -105.48 | 7598 | |
| Omega | city | Colorado | United States | 40.54 | -105.08 | 5029 | |
| Ophir | city | Colorado | United States | 37.86 | -107.83 | 10068 | |
| Ophir Loop | city | Colorado | United States | 37.86 | -107.87 | 10098 | |
| Orchard | city | Colorado | United States | 40.33 | -104.12 | 4402 | |
| Orchard City | city | Colorado | United States | 38.83 | -107.97 | 5403 | |
| Orchard Mesa | city | Colorado | United States | 39.04 | -108.55 | 4599 | |
| Orchard Park | city | Colorado | United States | 38.47 | -105.23 | 5869 | |
| Ordway | city | Colorado | United States | 38.22 | -103.76 | 4297 | |
| Ormega | city | Colorado | United States | 37.96 | -103.59 | 4206 | |
| Oro (historical) | city | Colorado | United States | 39.24 | -106.25 | 11017 | |
| Orodell | city | Colorado | United States | 40.01 | -105.33 | 5987 | |
| Orr | city | Colorado | United States | 38.11 | -103.54 | 4189 | |
| Orsa | city | Colorado | United States | 39.42 | -104.91 | 5997 | |
| Ortiz | city | Colorado | United States | 37.00 | -106.04 | 7942 | |
| Osier | city | Colorado | United States | 37.01 | -106.34 | 10068 | |
| Otis | city | Colorado | United States | 40.15 | -102.96 | 4360 | |
| Ouray | city | Colorado | United States | 38.02 | -107.67 | 7798 | |
| Ovid | city | Colorado | United States | 40.96 | -102.39 | 3513 | |
| Owl Canyon | city | Colorado | United States | 40.76 | -105.18 | 5869 | |
| Oxford | city | Colorado | United States | 37.17 | -107.71 | 6709 | |
| Oxyoke | city | Colorado | United States | 39.30 | -105.20 | 6709 |