| Name | What | Region | Country | Lat | Long | Elev Ft. | Pop Est |
|---|
| Oak Creek | city | Colorado | United States | 40.275 | -106.95778 | 7493 | 253 |
| Oak Grove | city | Colorado | United States | 38.46 | -107.9275 | 5885 | 4246 |
| Occidental | city | Colorado | United States | 37.515 | -105.10639 | 7706 | 187 |
| Oehlmann Park | city | Colorado | United States | 39.51889 | -105.25861 | 8303 | 4820 |
| Offield Place | city | Colorado | United States | 40.98583 | -108.6625 | 6614 | 10 |
| Ohio | city | Colorado | United States | 38.56667 | -106.61111 | 8930 | 117 |
| Olathe | city | Colorado | United States | 38.605 | -107.98167 | 5396 | 400 |
| Old Fort Bent historical | city | Colorado | United States | 38.04056 | -103.42889 | 3996 | 381 |
| Old Fort Lyons | city | Colorado | United States | 38.09583 | -102.77222 | 3697 | 895 |
| Old Fort Vasquez historical | city | Colorado | United States | 40.19444 | -104.82056 | 4872 | 1928 |
| Old Homestead | city | Colorado | United States | 40.44028 | -106.14306 | 8799 | 42 |
| Old Mountain View historical | city | Colorado | United States | 38.83389 | -104.99083 | 9583 | 4414 |
| Old Roach | city | Colorado | United States | 40.92444 | -106.11667 | 9399 | 104 |
| Old Wells | city | Colorado | United States | 38.9 | -102.32583 | 4196 | 98 |
| Olney Springs | city | Colorado | United States | 38.16611 | -103.94417 | 4343 | 634 |
| Olympus Heights | city | Colorado | United States | 40.37778 | -105.48333 | 7598 | 843 |
| Omega | city | Colorado | United States | 40.53972 | -105.08 | 5019 | 73438 |
| Ophir | city | Colorado | United States | 37.85694 | -107.83194 | 9790 | 327 |
| Ophir Loop | city | Colorado | United States | 37.85972 | -107.86778 | 10098 | 398 |
| Orchard | city | Colorado | United States | 40.33111 | -104.11778 | 4402 | 241 |
| Orchard City | city | Colorado | United States | 38.82833 | -107.97028 | 5449 | 1494 |
| Orchard Mesa | city | Colorado | United States | 39.04306 | -108.55167 | 4599 | 46217 |
| Orchard Park | city | Colorado | United States | 38.47222 | -105.22778 | 5459 | 15920 |
| Ordway | city | Colorado | United States | 38.21806 | -103.75556 | 4297 | 243 |
| Ormega | city | Colorado | United States | 37.96083 | -103.58583 | 4206 | 5117 |
| Oro | city | Colorado | United States | 39.23528 | -106.25167 | 11017 | 3392 |
| Orodell | city | Colorado | United States | 40.015 | -105.32472 | 5987 | 59716 |
| Orr | city | Colorado | United States | 38.1075 | -103.53472 | 4146 | 560 |
| Orsa | city | Colorado | United States | 39.42222 | -104.91333 | 5997 | 8587 |
| Ortiz | city | Colorado | United States | 37.00417 | -106.04361 | 7942 | 249 |
| Osier | city | Colorado | United States | 37.01333 | -106.33583 | 9806 | 47 |
| Otis | city | Colorado | United States | 40.14889 | -102.9625 | 4353 | 103 |
| Ouray | city | Colorado | United States | 38.02278 | -107.67083 | 8559 | 257 |
| Ovid | city | Colorado | United States | 40.96056 | -102.3875 | 3513 | 536 |
| Owl Canyon | city | Colorado | United States | 40.7625 | -105.175 | 5784 | 465 |
| Oxford | city | Colorado | United States | 37.16889 | -107.71361 | 6604 | 721 |
| Oxyoke | city | Colorado | United States | 39.30306 | -105.19778 | 6548 | 584 |
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