Feature Name | Class | Elev. meters | County | Latitude DMS | Longitude DMS |
| Union Mine | Mine | 2590 | Pitkin | 39 21 15 N | 107 18 47 W |
| Union Mine | Mine | 3759 | San Juan | 37 56 35 N | 107 36 05 W |
| Union Mountain | Summit | 3748 | Summit | 39 28 06 N | 106 10 30 W |
| Union Pacific Mine | Mine | 2781 | Boulder | 40 04 24 N | 105 30 26 W |
| Union Park | Flat | 2976 | Gunnison | 38 46 20 N | 106 33 42 W |
| Union Park Cow Camp | Locale | 2949 | Gunnison | 38 46 13 N | 106 34 39 W |
| Union Reservoir | Reservoir | 1511 | Weld | 40 10 24 N | 105 02 38 W |
| Union Reservoir Ditch | Canal | 1500 | Weld | 40 09 44 N | 105 02 41 W |
| Union Ridge Park | Park | | Jefferson | 39 43 24 N | 105 08 34 W |
| Union School | Locale | 1259 | Morgan | 40 22 42 N | 103 29 54 W |
| Union School | School | 1256 | Prowers | 38 51 14 N | 102 15 33 W |
| Union Square Park | Park | | Jefferson | 39 42 58 N | 105 08 21 W |
| Union Station | Locale | 1581 | Denver | 39 45 14 N | 105 00 01 W |
| Union Tunnel Mine | Mine | 2539 | Clear Creek | 39 44 47 N | 105 34 10 W |
| Union Valley Cemetery | Cemetery | 1190 | Bent | 38 05 46 N | 102 57 29 W |
| Unitarian Church (historical) | Church | 1638 | Boulder | 40 00 48 N | 105 17 02 W |
| Unitarian Fellowship Church | Church | 1995 | La Plata | 37 16 20 N | 107 52 40 W |
| United Building Stone Quarry | Mine | 1639 | Boulder | 40 13 31 N | 105 16 03 W |
| United Church of Christ - Hillcrest Congregational Worship | Church | 1787 | Montrose | 38 28 53 N | 107 51 26 W |
| United Empire Mine | Mine | 2523 | Boulder | 40 03 49 N | 105 24 27 W |
| United Freeland Mine | Mine | 2420 | Clear Creek | 39 45 53 N | 105 35 58 W |
| United Gold Mine | Mine | 2370 | Clear Creek | 39 45 32 N | 105 33 22 W |
| United Methodist Church | Church | 1724 | Delta | 38 52 07 N | 107 35 47 W |
| United Methodist Church | Church | 2117 | Montezuma | 37 28 32 N | 108 29 58 W |
| United Methodist Church | Church | 2135 | Montezuma | 37 20 43 N | 108 17 43 W |
| United Methodist Church | Church | 1769 | Montrose | 38 28 50 N | 107 52 28 W |
| United Mines | Mine | 1632 | Boulder | 40 01 08 N | 105 16 41 W |
| United Mines Shaft | Mine | 3235 | Mineral | 37 52 46 N | 106 56 01 W |
| United Nations Park | Park | 1597 | Denver | 39 44 30 N | 104 59 15 W |
| United Sand and Gravel Pit | Mine | 1421 | Mesa | 39 04 13 N | 108 36 37 W |
| United States Air Force Academy | School | 2034 | El Paso | 38 59 25 N | 104 51 30 W |
| United States Air Force Academy Airstrip | Airport | 1995 | El Paso | 38 58 10 N | 104 48 48 W |
| United States Air Force Academy Cemetery | Cemetery | 2069 | El Paso | 39 00 56 N | 104 51 20 W |
| United States Army Fitzsimons General Hospital (historical) | Hospital | 1640 | Adams | 39 44 43 N | 104 50 14 W |
| United States Customhouse | Building | | Denver | 39 44 56 N | 104 59 18 W |
| United States Government Reservoir | Reservoir | 1829 | Huerfano | 37 49 15 N | 104 29 09 W |
| United States Mountain | Summit | 3967 | Ouray | 37 57 24 N | 107 44 21 W |
| United States Postal Service Annex | Post Office | 1600 | Boulder | 40 01 08 N | 105 14 44 W |
| Unity Church | Church | 1620 | Boulder | 40 01 43 N | 105 15 53 W |
| Unity Church | Church | 1429 | Mesa | 39 05 55 N | 108 33 11 W |
| Unity Tunnel | Mine | 3555 | San Juan | 37 48 05 N | 107 37 08 W |
| University Hill School | School | 1664 | Boulder | 40 00 12 N | 105 16 18 W |
| University Hills Mall | Locale | 1651 | Denver | 39 40 00 N | 104 56 22 W |
| University Hills Plaza | Locale | 1651 | Denver | 39 40 13 N | 104 56 20 W |
| University Hospital Heliport | Airport | 1624 | Denver | 39 43 54 N | 104 56 18 W |
| University Mine | Mine | 2901 | Clear Creek | 39 47 36 N | 105 33 56 W |
| University of Colorado | School | 1642 | Boulder | 40 00 20 N | 105 15 52 W |
| University of Colorado - Colorado Springs Campus | School | 1949 | El Paso | 38 53 33 N | 104 47 59 W |
| University of Colorado Camp | Locale | 2894 | Boulder | 40 01 53 N | 105 32 14 W |
| University of Colorado Center | School | 1887 | Montezuma | 37 20 56 N | 108 35 08 W |
| University of Colorado Health Services Center | Hospital | 1626 | Denver | 39 43 50 N | 104 56 21 W |
| University of Colorado Observatory | Locale | 2658 | Boulder | 39 56 49 N | 105 31 03 W |
| University of Colorado Quarry | Mine | 1639 | Boulder | 40 13 31 N | 105 16 03 W |
| University of Denver | School | 1640 | Denver | 39 40 36 N | 104 57 44 W |
| University of Denver - Park Hill Campus | School | 1631 | Denver | 39 44 45 N | 104 54 18 W |
| University of Kansas Geology Summer Camp | Locale | 1902 | Fremont | 38 36 05 N | 105 13 30 W |
| University of Northern Colorado | School | 1436 | Weld | 40 24 36 N | 104 41 35 W |
| University of Oklahoma Summer Geology Camp | Locale | 1710 | Fremont | 38 28 42 N | 105 05 37 W |
| University of Southern Colorado | School | 1503 | Pueblo | 38 18 30 N | 104 34 42 W |
| University Park Elementary School | School | 1644 | Denver | 39 40 27 N | 104 57 01 W |
| University Park Station Denver Post Office | Post Office | | Denver | 39 40 47 N | 104 56 37 W |
| Up-to-date Mine | Mine | 3049 | Boulder | 39 59 35 N | 105 34 36 W |
| Upham Gulch | Valley | | Boulder | 40 00 14 N | 105 25 56 W |
| Upland and Home Ditch Number 1 | Canal | 2462 | Jackson | 40 42 28 N | 106 16 02 W |
| Upper 4A Mountain | Summit | 2711 | Garfield | 39 36 28 N | 108 36 57 W |
| Upper Baltic Shaft | Mine | 3881 | Park | 39 17 42 N | 106 10 15 W |
| Upper Barton Camp | Locale | 1801 | Larimer | 40 55 01 N | 105 00 26 W |
| Upper Bear Creek Ditch | Canal | 1663 | Boulder | 39 58 05 N | 105 14 24 W |
| Upper Bear Creek School | School | 2231 | Huerfano | 37 28 46 N | 104 53 14 W |
| Upper Beaver Cemetery | Cemetery | 1823 | Fremont | 38 32 40 N | 105 01 52 W |
| Upper Beaver Creek Campground | Locale | 2592 | Rio Grande | 37 36 21 N | 106 40 39 W |
| Upper Beaver Meadow | Flat | 3140 | Rio Grande | 37 30 03 N | 106 37 24 W |
| Upper Beaver Reservoir | Reservoir | 2468 | Dolores | 37 41 21 N | 108 23 58 W |
| Upper Beaver School | School | 1828 | Fremont | 38 33 03 N | 105 01 55 W |
| Upper Bench Trail | Trail | 2667 | Mesa | 38 32 30 N | 108 37 51 W |
| Upper Blue Dam | Dam | 3998 | Summit | 39 24 06 N | 106 06 08 W |
| Upper Blue Reservoir | Reservoir | 3998 | Summit | 39 24 06 N | 106 06 08 W |
| Upper Bostwick Park | Flat | 2240 | Montrose | 38 29 16 N | 107 41 48 W |
| Upper Burke Windmill | Locale | 1599 | Las Animas | 37 26 08 N | 104 00 57 W |
| Upper Burro Canyon | Valley | | Las Animas | 37 14 29 N | 104 46 44 W |
| Upper Burro Canyon School | School | 2203 | Las Animas | 37 13 46 N | 104 46 10 W |
| Upper Cabin Creek Hydroelectric Dam | Dam | 3403 | Clear Creek | 39 38 60 N | 105 43 08 W |
| Upper Cabin Creek Hydroelectric Reservoir | Reservoir | 3403 | Clear Creek | 39 38 60 N | 105 43 08 W |
| Upper Cabin Creek Reservoir | Reservoir | 3368 | Clear Creek | 39 39 03 N | 105 43 09 W |
| Upper Camp Bird | Locale | 3438 | Ouray | 37 56 58 N | 107 43 47 W |
| Upper Camp Lake | Lake | 3422 | Eagle | 39 26 39 N | 106 34 04 W |
| Upper Camp Lake | Lake | 3270 | Larimer | 40 40 58 N | 105 55 26 W |
| Upper Cataract Lake | Lake | 3280 | Summit | 39 47 37 N | 106 20 06 W |
| Upper Chatauqua Mine | Mine | 3441 | Summit | 39 33 29 N | 105 52 03 W |
| Upper Chicosa Reservoir | Reservoir | 1469 | Pueblo | 38 01 41 N | 104 19 01 W |
| Upper Chieftain Mine | Mine | 4013 | San Miguel | 37 55 08 N | 107 44 24 W |
| Upper Chinns Dam | Dam | 3390 | Clear Creek | 39 49 00 N | 105 41 56 W |
| Upper Chinns Reservoir | Reservoir | 3390 | Clear Creek | 39 49 00 N | 105 41 56 W |
| Upper Church Ditch | Canal | 1744 | Jefferson | 39 54 38 N | 105 08 39 W |
| Upper Church Lake | Reservoir | 1696 | Boulder | 39 54 19 N | 105 06 11 W |
| Upper Church Lakes Dam | Dam | 1695 | Jefferson | 39 54 19 N | 105 06 11 W |
| Upper Clipper Mine | Mine | 3553 | Park | 39 18 10 N | 106 09 28 W |
| Upper Cogdill Lake | Reservoir | 2275 | Moffat | 40 58 10 N | 107 20 12 W |
| Upper Coney Lake | Lake | 3336 | Boulder | 40 06 27 N | 105 37 31 W |
| Upper Cottonwood Reservoir | Reservoir | 1816 | Rio Blanco | 39 56 45 N | 108 54 07 W |
| Upper Cow Camp | Locale | 2765 | Gunnison | 38 51 34 N | 107 22 48 W |
| Upper Craig Draw Reservoir | Reservoir | 2468 | Montrose | 38 09 12 N | 108 10 14 W |
| Upper Craven Dam | Dam | 2531 | Grand | 40 06 54 N | 106 30 08 W |
| Upper Craven Reservoir | Reservoir | 2531 | Grand | 40 06 54 N | 106 30 08 W |
| Upper Crystal Lake | Lake | 3925 | Summit | 39 26 07 N | 106 06 21 W |
| Upper Derby Lake | Reservoir | 1607 | Adams | 39 49 03 N | 104 50 06 W |
| Upper Derby Lake Dam | Dam | 1608 | Adams | 39 49 06 N | 104 50 02 W |
| Upper Desert Tank | Reservoir | 2561 | Ouray | 38 05 45 N | 107 51 23 W |
| Upper Diamond Lake | Lake | 3574 | Boulder | 39 59 31 N | 105 40 23 W |
| Upper Disaster Falls | Falls | 1777 | Moffat | 40 39 01 N | 108 56 00 W |