Feature Name | Class | Elev. meters | County | Latitude DMS | Longitude DMS |
| Union Junction (historical) | Locale | 1581 | Deer Lodge | 46 07 35 N | 112 55 08 W |
| Union Mine | Mine | 2119 | Jefferson | 46 17 26 N | 111 56 32 W |
| Union Mine | Mine | 1786 | Madison | 45 31 08 N | 112 11 56 W |
| Union Mine | Mine | 1804 | Madison | 45 31 05 N | 112 11 51 W |
| Union Mountain | Summit | 2321 | Flathead | 48 03 21 N | 113 16 41 W |
| Union Oil Company of California Spur | Locale | 1131 | Glacier | 48 35 10 N | 112 12 03 W |
| Union Peak | Summit | 2079 | Granite | 46 48 28 N | 113 23 56 W |
| Union Peak | Summit | 2671 | Lake | 47 37 31 N | 113 38 23 W |
| Union Post Office (historical) | Post Office | 883 | Dawson | 47 11 14 N | 105 18 23 W |
| Union School (historical) | School | 915 | Dawson | 47 12 36 N | 105 19 18 W |
| Union School (historical) | School | 1080 | Toole | 48 18 20 N | 111 38 38 W |
| Unionville | Populated Place | 1498 | Lewis and Clark | 46 32 29 N | 112 05 06 W |
| Unionville Post Office (historical) | Post Office | 1498 | Lewis and Clark | 46 32 29 N | 112 05 06 W |
| Unionville School (historical) | School | 1498 | Lewis and Clark | 46 32 29 N | 112 05 06 W |
| Unitarian - Universalist Fellowship | Church | 978 | Missoula | 46 51 35 N | 113 59 31 W |
| Unitarian Universal Fellowship | Church | 901 | Flathead | 48 11 45 N | 114 18 46 W |
| United Bethel Methodist Church | Church | 1559 | Madison | 45 27 20 N | 112 11 49 W |
| United Brethren Church (historical) | Church | 945 | Fallon | 46 35 05 N | 104 05 05 W |
| United Christian Church | Church | 743 | McCone | 47 25 06 N | 105 35 01 W |
| United Church of Christ Congregational | Church | 1126 | Teton | 47 42 57 N | 111 41 13 W |
| United Church of Christ Congregational | Church | 1214 | Teton | 47 36 53 N | 111 58 49 W |
| United Community Church | Church | 987 | Rosebud | 45 52 58 N | 106 37 30 W |
| United Congregational Church | Church | 1683 | Silver Bow | 45 59 10 N | 112 29 34 W |
| United Dakota Presbyterian Church | Church | 609 | Roosevelt | 48 05 19 N | 105 38 50 W |
| United Grain Corporation Elevator (historical) | Locale | 595 | Roosevelt | 48 06 26 N | 105 09 51 W |
| United Methodist Camp | Locale | 888 | Lake | 47 54 02 N | 114 12 03 W |
| United Methodist Church | Church | 885 | Big Horn | 45 43 58 N | 107 36 30 W |
| United Methodist Church | Church | 721 | Blaine | 48 31 60 N | 108 47 03 W |
| United Methodist Church | Church | 742 | Blaine | 48 35 32 N | 109 13 48 W |
| United Methodist Church | Church | 1172 | Broadwater | 46 19 20 N | 111 31 05 W |
| United Methodist Church | Church | 1392 | Cascade | 47 05 54 N | 110 50 19 W |
| United Methodist Church | Church | 754 | Daniels | 48 47 28 N | 105 25 18 W |
| United Methodist Church | Church | 628 | Dawson | 47 06 21 N | 104 42 50 W |
| United Methodist Church | Church | 762 | Dawson | 47 38 34 N | 105 04 09 W |
| United Methodist Church | Church | 1608 | Deer Lodge | 46 07 42 N | 112 57 05 W |
| United Methodist Church | Church | 1201 | Fergus | 47 03 53 N | 109 25 47 W |
| United Methodist Church | Church | 994 | Fergus | 47 33 28 N | 109 22 38 W |
| United Methodist Church | Church | 1062 | Fergus | 47 01 35 N | 108 48 10 W |
| United Methodist Church | Church | 1242 | Gallatin | 45 53 33 N | 111 33 08 W |
| United Methodist Church | Church | 896 | Lake | 47 19 12 N | 114 05 38 W |
| United Methodist Church | Church | 918 | Lake | 47 40 51 N | 114 09 31 W |
| United Methodist Church | Church | 929 | Lake | 47 31 40 N | 114 06 11 W |
| United Methodist Church | Church | 901 | Petroleum | 47 00 12 N | 108 21 11 W |
| United Methodist Church | Church | 623 | Sheridan | 48 46 18 N | 104 33 38 W |
| United Methodist Church | Church | 1161 | Teton | 47 48 40 N | 112 10 31 W |
| United Methodist Church | Church | 662 | Valley | 48 23 40 N | 107 05 11 W |
| United Methodist Church | Church | 994 | Valley | 48 51 27 N | 106 24 23 W |
| United Methodist Church | Church | 1415 | Wheatland | 46 40 45 N | 109 45 13 W |
| United Methodist Church | Church | 810 | Wibaux | 46 59 06 N | 104 11 19 W |
| United Methodist Church (historical) | Church | 589 | Roosevelt | 48 08 40 N | 104 31 01 W |
| United Methodist Church (historical) | Church | 1175 | Wheatland | 46 20 33 N | 109 31 30 W |
| United Methodist Community Church | Church | 924 | Hill | 48 33 18 N | 110 25 20 W |
| United Mine Workers of America Cemetery | Cemetery | 998 | Musselshell | 46 24 56 N | 108 33 24 W |
| United Pentecostal Church | Church | 885 | Big Horn | 45 44 22 N | 107 36 37 W |
| United Pentecostal Church | Church | 1469 | Gallatin | 45 40 42 N | 111 01 51 W |
| United Pentecostal Church | Church | 759 | Hill | 48 33 04 N | 109 40 27 W |
| United Pentecostal Church | Church | 1246 | Lewis and Clark | 46 35 30 N | 112 02 08 W |
| United Pentecostal Church | Church | 965 | Missoula | 46 50 22 N | 114 02 14 W |
| United Pentecostal Church | Church | 1372 | Park | 45 40 13 N | 110 33 18 W |
| United Pentecostal Church of Butte | Church | 1675 | Silver Bow | 46 00 01 N | 112 32 07 W |
| United States Air Force Hospital | Hospital | 1050 | Cascade | 47 30 60 N | 111 11 33 W |
| United States Fish and Culture Development Center | Locale | 1497 | Gallatin | 45 42 32 N | 110 59 24 W |
| United States Forest Service Aerial Fire Depot | Locale | 977 | Missoula | 46 55 30 N | 114 05 34 W |
| United States Forest Service Fire Station | Locale | 971 | Sanders | 47 32 37 N | 115 36 23 W |
| United States Forest Service Lab | Building | 984 | Missoula | 46 51 27 N | 113 59 02 W |
| United States Forest Service Lyon Work Camp | Locale | 1804 | Madison | 44 53 55 N | 111 35 53 W |
| United States Forest Service West Fork Camp | Locale | 1794 | Madison | 44 53 15 N | 111 35 02 W |
| United States Grant Mines | Mine | 1870 | Madison | 45 16 54 N | 111 56 36 W |
| United States High Altitude Sports Center | Locale | 1690 | Silver Bow | 45 57 50 N | 112 28 33 W |
| United States Number 2 Dam | Dam | 1078 | Powder River | 45 09 48 N | 105 39 44 W |
| United States Sheep Experiment Station | Park | 2640 | Beaverhead | 44 33 60 N | 111 35 03 W |
| Unity Church of Bozeman | Church | 1498 | Gallatin | 45 39 28 N | 111 02 05 W |
| Unity Church of Missoula | Church | 1116 | Missoula | 46 48 30 N | 114 01 43 W |
| Unity Church of Truth | Church | 1044 | Cascade | 47 29 29 N | 111 16 41 W |
| Unity Post Office (historical) | Post Office | 1631 | Meagher | 46 27 13 N | 111 02 03 W |
| Unity School (historical) | School | 960 | Garfield | 46 56 23 N | 107 27 27 W |
| Unity School (historical) | School | 1631 | Meagher | 46 27 13 N | 111 02 03 W |
| Unity Truth Center | Church | 1374 | Park | 45 39 36 N | 110 33 49 W |
| University Beacon | Locale | 1768 | Missoula | 46 51 11 N | 113 55 45 W |
| University Center | Building | 983 | Missoula | 46 51 39 N | 113 58 58 W |
| University Congregational Church | Church | 978 | Missoula | 46 51 36 N | 113 59 32 W |
| University Hall | Building | 984 | Missoula | 46 51 36 N | 113 59 02 W |
| University Heights | Populated Place | 1245 | Ravalli | 46 02 01 N | 114 12 56 W |
| University Mountain | Summit | 1739 | Missoula | 46 51 08 N | 113 56 07 W |
| University of Great Falls Library | Building | 1048 | Cascade | 47 29 27 N | 111 16 14 W |
| University of Montana | School | 984 | Missoula | 46 51 37 N | 113 59 01 W |
| University of Montana Biological Station | Locale | 892 | Lake | 47 52 38 N | 114 01 53 W |
| University of Montana Golf Course | Locale | 987 | Missoula | 46 50 40 N | 113 59 33 W |
| University of Montana Soccer Field | Park | 978 | Missoula | 46 50 50 N | 113 59 38 W |
| University Square Shopping Center | Locale | 1474 | Gallatin | 45 40 36 N | 111 03 58 W |
| Unknown Creek | Stream | | Treasure | 46 12 26 N | 107 24 52 W |
| Unnamed Creek | Stream | | Mineral | 47 17 40 N | 115 18 09 W |
| Unnamed Lake | Lake | 2181 | Lewis and Clark | 47 45 23 N | 113 04 10 W |
| Unnamed Spring Creek | Stream | | Madison | 45 38 51 N | 112 17 15 W |
| Uoll Heights Post Office (historical) | Post Office | 836 | Garfield | 46 58 48 N | 106 14 00 W |
| Up Up Creek | Stream | | Mineral | 47 20 51 N | 115 22 39 W |
| Up Up Mountain | Summit | 1818 | Mineral | 47 19 57 N | 115 20 37 W |
| Uper Ox Frame Gulch Mine | Mine | 1671 | Fergus | 47 08 46 N | 109 14 08 W |
| Upham Creek | Stream | | Lincoln | 48 13 59 N | 115 50 24 W |
| Upham Creek | Stream | | Mineral | 47 09 13 N | 114 54 59 W |
| Uphans Reservoir | Reservoir | 714 | Valley | 48 06 38 N | 106 55 08 W |
| Uphaus Ranch | Locale | 693 | Valley | 48 11 11 N | 106 51 43 W |
| Uphill Creek | Stream | | Beaverhead | 45 29 47 N | 112 53 18 W |
| Uphill Creek | Stream | | Liberty | 48 11 49 N | 111 04 58 W |
| Upland Ditch | Canal | 1558 | Park | 45 22 27 N | 110 38 23 W |
| Upper Aero Lake | Lake | 3096 | Park | 45 07 40 N | 109 50 25 W |
| Upper Alder Gulch Mine | Mine | 1291 | Phillips | 47 55 10 N | 108 32 55 W |
| Upper Alice E Mine | Mine | 2643 | Park | 45 01 58 N | 109 55 41 W |
| Upper Amazon-Dixie Mine | Mine | 1475 | Mineral | 47 25 45 N | 115 42 14 W |
| Upper Anderson Meadows | Swamp | 2213 | Beaverhead | 45 31 30 N | 113 11 01 W |