Feature Name | Class | Elev. meters | County | Latitude DMS | Longitude DMS |
| Hyde Creek | Stream | | Glacier | 48 22 14 N | 113 13 15 W |
| Hyde Creek | Stream | | Madison | 45 02 02 N | 111 40 24 W |
| Hyde Creek | Stream | | Mineral | 46 48 34 N | 114 37 51 W |
| Hyde Creek Ditch | Canal | 1802 | Madison | 45 00 42 N | 111 41 32 W |
| Hyde Creek School (historical) | School | 1655 | Fergus | 46 45 32 N | 109 37 03 W |
| Hyde Creek Trail | Trail | 2809 | Madison | 44 58 30 N | 111 47 12 W |
| Hyde Number 2 Dam | Dam | 757 | Prairie | 46 38 18 N | 105 03 44 W |
| Hyde Post Office (historical) | Post Office | 1311 | Gallatin | 45 43 40 N | 111 29 43 W |
| Hyde Post Office (historical) | Post Office | 795 | Treasure | 46 19 12 N | 107 07 42 W |
| Hydro Post Office (historical) | Post Office | 845 | Blaine | 48 58 40 N | 109 08 08 W |
| Hydro School (historical) | School | 845 | Blaine | 48 58 20 N | 109 08 06 W |
| Hyem Ranch | Locale | 1516 | Carbon | 45 18 22 N | 109 23 43 W |
| Hyfield Post Office (historical) | Post Office | 1338 | Musselshell | 46 44 57 N | 108 57 28 W |
| Hyland Heights Park | Park | 1032 | Cascade | 47 29 01 N | 111 18 08 W |
| Hyman Creek | Stream | | Park | 45 09 22 N | 110 23 06 W |
| Hymer Coulee | Valley | | Phillips | 48 36 48 N | 107 30 01 W |
| Hyndman (historical) | Locale | 1565 | Jefferson | 46 14 17 N | 112 08 48 W |
| Hysham | Locale | 809 | Treasure | 46 17 32 N | 107 14 27 W |
| Hysham | Populated Place | 811 | Treasure | 46 17 34 N | 107 14 03 W |
| Hysham Airport | Airport | 800 | Treasure | 46 17 21 N | 107 11 47 W |
| Hysham Baptist Church | Church | 811 | Treasure | 46 17 34 N | 107 14 03 W |
| Hysham Canal | Canal | 816 | Treasure | 46 15 30 N | 107 08 45 W |
| Hysham Community Elevator | Locale | 811 | Treasure | 46 17 34 N | 107 14 03 W |
| Hysham Community Health Clinic | Hospital | 811 | Treasure | 46 17 34 N | 107 14 03 W |
| Hysham Main Canal | Canal | 822 | Treasure | 46 16 27 N | 107 14 15 W |
| Hysham Post Office | Post Office | 811 | Treasure | 46 17 34 N | 107 14 00 W |
| Hysham Re-Lift Canal | Canal | 836 | Treasure | 46 15 11 N | 107 17 58 W |
| Hysham Rest Area | Locale | 882 | Treasure | 46 13 06 N | 107 14 59 W |
| Hysham School | School | 812 | Treasure | 46 17 33 N | 107 13 52 W |
| Hysham School (historical) | School | 805 | Treasure | 46 17 38 N | 107 14 52 W |
| Hystens Ditch | Canal | 1243 | Broadwater | 46 09 30 N | 111 34 39 W |
| I U Reservoir Dam | Dam | 1129 | Blaine | 48 05 18 N | 109 17 03 W |
| I-94 Trailer Park | Populated Place | 623 | Dawson | 47 06 18 N | 104 43 56 W |
| Ibex Creek | Stream | | Sanders | 48 12 40 N | 115 43 39 W |
| Ibex Guard Station | Locale | 2043 | Park | 46 00 12 N | 110 26 34 W |
| Ibex Mountain | Summit | 2432 | Flathead | 47 48 47 N | 113 12 57 W |
| Ibex Mountain | Summit | 2221 | Park | 45 59 13 N | 110 28 04 W |
| Ibex Peak | Summit | 2297 | Sanders | 48 11 50 N | 115 45 05 W |
| ICAA Radio Range Station | Tower | 1461 | Park | 45 40 11 N | 110 28 40 W |
| Ice Cave Spring | Spring | 960 | Custer | 46 25 18 N | 105 37 12 W |
| Ice Cream Butte | Summit | 862 | Rosebud | 46 24 33 N | 106 31 42 W |
| Ice Creek | Stream | | Madison | 45 04 18 N | 112 01 52 W |
| Ice Creek | Stream | | Meagher | 46 37 32 N | 110 45 03 W |
| Ice Creek | Stream | | Sanders | 47 51 17 N | 115 17 54 W |
| Ice House Gulch | Valley | | Deer Lodge | 46 08 30 N | 113 00 00 W |
| Ice Pond | Lake | 1974 | Beaverhead | 45 23 36 N | 113 29 07 W |
| Ice Pond | Lake | 1900 | Jefferson | 46 09 41 N | 112 22 35 W |
| Ice Skating Rink Dam | Dam | 833 | Hill | 48 50 48 N | 109 38 03 W |
| Iceberg Creek | Stream | | Glacier | 48 49 05 N | 113 42 56 W |
| Iceberg Lake | Lake | 1859 | Glacier | 48 48 44 N | 113 44 59 W |
| Iceberg Lake Trail | Trail | 1871 | Glacier | 48 49 31 N | 113 43 58 W |
| Iceberg Notch | Gap | 2535 | Glacier | 48 49 09 N | 113 45 22 W |
| Iceberg Peak | Summit | 2789 | Glacier | 48 48 52 N | 113 45 36 W |
| Iceberg Peak | Summit | 3513 | Park | 45 07 50 N | 109 53 16 W |
| Icebox Spring | Spring | 1170 | Carter | 45 37 15 N | 104 11 54 W |
| Icefloe Lake | Lake | 2277 | Lake | 47 22 11 N | 113 54 23 W |
| Ichpair Creek | Stream | | Valley | 48 47 28 N | 106 58 17 W |
| Ida M Mine | Mine | 2209 | Jefferson | 46 19 57 N | 112 12 48 W |
| Ida May Mine | Mine | 2296 | Jefferson | 46 25 09 N | 112 13 50 W |
| Ida May Mine | Mine | 2299 | Jefferson | 46 25 15 N | 112 13 46 W |
| Ida Mine | Mine | 1499 | Jefferson | 46 04 54 N | 111 50 35 W |
| Ida Mine | Mine | 1506 | Jefferson | 46 04 55 N | 111 50 33 W |
| Ida Post Office (historical) | Post Office | 1032 | Cascade | 47 33 10 N | 111 35 03 W |
| Idaho Creek | Stream | | Flathead | 48 05 57 N | 114 33 41 W |
| Idaho Creek | Stream | | Madison | 45 11 51 N | 112 08 34 W |
| Idaho Gulch | Valley | | Mineral | 47 11 38 N | 114 52 25 W |
| Idaho Mine | Mine | 1723 | Madison | 45 32 13 N | 111 46 48 W |
| Idaville (historical) | Locale | 1845 | Lewis and Clark | 46 44 55 N | 112 18 43 W |
| Iddings Peak | Summit | 3322 | Park | 46 00 49 N | 110 19 01 W |
| Idenity Preserve Grain Company Elevator (historical) | Locale | 752 | Daniels | 48 47 36 N | 105 25 10 W |
| Idiom Island | Island | 601 | Richland | 47 21 47 N | 104 23 59 W |
| Idler Mine | Mine | 1768 | Madison | 45 36 18 N | 112 28 51 W |
| Idlewile (historical) | Populated Place | 628 | Valley | 48 02 39 N | 106 25 49 W |
| Idlewise Court | Populated Place | 961 | Lake | 48 01 22 N | 114 04 03 W |
| Iehl Dam | Dam | 803 | Dawson | 47 20 18 N | 104 57 08 W |
| Iff Gulch | Valley | | Sanders | 47 52 57 N | 115 43 56 W |
| Ihmsen Well | Well | 840 | Chouteau | 48 13 42 N | 110 12 03 W |
| Ike Williams Gulch | Valley | | Ravalli | 46 03 05 N | 114 11 11 W |
| Ikes Butte | Summit | 1264 | Liberty | 48 58 42 N | 111 10 36 W |
| Ikey Creek | Stream | | Carter | 45 30 06 N | 104 35 54 W |
| Iliad | Populated Place | 897 | Chouteau | 47 47 55 N | 109 47 10 W |
| Iliad Post Office (historical) | Post Office | 897 | Chouteau | 47 47 55 N | 109 47 10 W |
| Iliad School (historical) | School | 877 | Chouteau | 47 49 47 N | 109 48 57 W |
| Illinois Gulch | Valley | | Mineral | 47 03 21 N | 115 02 55 W |
| Illinois Gulch | Valley | | Powell | 46 40 23 N | 112 33 08 W |
| Illinois Peak | Summit | 2337 | Mineral | 47 01 36 N | 115 04 16 W |
| Illinois Ridge | Ridge | 1882 | Powell | 46 41 20 N | 112 33 08 W |
| Illinois School (historical) | School | 1106 | Fergus | 47 28 36 N | 109 48 26 W |
| Illmont School (historical) | School | 735 | McCone | 47 50 46 N | 106 03 26 W |
| Image Lake | Lake | 1788 | Sanders | 47 45 42 N | 115 17 31 W |
| Imelda Lake | Lake | 2977 | Park | 45 09 58 N | 109 54 40 W |
| Immaculate Conception Catholic Church | Church | 805 | Chouteau | 47 49 15 N | 110 40 17 W |
| Immaculate Conception Catholic Church | Church | 893 | Lake | 47 41 30 N | 114 08 53 W |
| Immaculate Conception Catholic Church | Church | 608 | Roosevelt | 48 05 13 N | 105 38 42 W |
| Immaculate Conception Chapel | Church | 898 | Flathead | 48 11 05 N | 114 20 33 W |
| Immaculate Conception Church | Church | 1391 | Powell | 46 23 47 N | 112 43 48 W |
| Immaculate Conception Church | Church | 623 | Roosevelt | 48 20 00 N | 104 29 19 W |
| Immaculate Conception Church | Church | 767 | Rosebud | 46 16 13 N | 106 40 40 W |
| Immaculate Conception Church | Church | 1778 | Silver Bow | 46 00 59 N | 112 33 19 W |
| Immaculate Conception Mission | Church | 579 | Lincoln | 48 27 48 N | 115 53 23 W |
| Immaculate Conception Mission | Church | 1415 | Wheatland | 46 40 45 N | 109 45 13 W |
| Immaculate Conception School (historical) | School | 608 | Roosevelt | 48 05 12 N | 105 38 42 W |
| Immaculate Heart of Mary Church | Church | 1032 | Cascade | 47 31 28 N | 111 16 26 W |
| Immanual Lutheran Church | Church | 1231 | Stillwater | 45 31 14 N | 109 26 35 W |
| Immanuel Baptist Church | Church | 773 | Hill | 48 32 60 N | 109 41 03 W |
| Immanuel Cemetery | Cemetery | 635 | Sheridan | 48 39 51 N | 104 04 58 W |
| Immanuel Church | Church | 988 | Liberty | 48 53 08 N | 110 48 59 W |
| Immanuel Lutheran Cemetery | Cemetery | 805 | Dawson | 47 26 28 N | 104 40 23 W |
| Immanuel Lutheran Cemetery | Cemetery | 764 | McCone | 47 38 31 N | 105 29 34 W |
| Immanuel Lutheran Church | Church | 762 | McCone | 47 38 32 N | 105 29 31 W |