Feature Name | Class | Elev. meters | County | Latitude DMS | Longitude DMS |
| Solomon Ridge Trail | Trail | 1986 | Granite | 46 39 17 N | 113 42 24 W |
| Solomon Sportsmans Access | Locale | 1200 | Granite | 46 39 05 N | 113 39 40 W |
| Some Creek | Stream | | Powell | 47 27 43 N | 113 22 56 W |
| Somers | Populated Place | 889 | Flathead | 48 04 49 N | 114 13 17 W |
| Somers (historical) | Locale | 890 | Flathead | 48 04 50 N | 114 13 32 W |
| Somers Boat Launch | Locale | 883 | Flathead | 48 04 38 N | 114 14 10 W |
| Somers Fire Station | Building | 890 | Flathead | 48 04 48 N | 114 13 32 W |
| Somers Fishing Access Site | Locale | 883 | Flathead | 48 04 37 N | 114 14 13 W |
| Somers Junction (historical) | Locale | 900 | Flathead | 48 11 40 N | 114 20 03 W |
| Somers Post Office | Post Office | 890 | Flathead | 48 04 50 N | 114 13 32 W |
| Somers Reservoir | Reservoir | 753 | Valley | 48 06 15 N | 107 12 05 W |
| Somers School | School | 885 | Flathead | 48 05 14 N | 114 13 24 W |
| Sominski School (historical) | School | 844 | Wibaux | 46 52 03 N | 104 09 19 W |
| Sommer Haven Christian Church | Church | 1334 | Glacier | 48 33 25 N | 113 00 48 W |
| Son Prong | Stream | | Big Horn | 45 04 09 N | 106 17 38 W |
| Songstad Ranch | Locale | 1322 | Sweet Grass | 45 55 05 N | 109 56 06 W |
| Songster Butte | Summit | 1658 | Meagher | 46 50 26 N | 111 11 38 W |
| Songster Butte Mine | Mine | 1592 | Meagher | 46 50 37 N | 111 11 33 W |
| Sonielem Lake | Lake | 2117 | Lake | 47 19 09 N | 113 55 53 W |
| Sonielem Ridge | Ridge | 2783 | Lake | 47 19 13 N | 113 54 39 W |
| Sonju Mine | Mine | 1830 | Sanders | 47 37 30 N | 115 38 34 W |
| Sonnette | Populated Place | 1148 | Powder River | 45 24 47 N | 105 49 53 W |
| Sonny Coulee | Valley | | Garfield | 47 21 25 N | 106 32 35 W |
| Sonny Number 1 Dam | Dam | 762 | Garfield | 47 22 12 N | 106 32 56 W |
| Sonora Gulch | Valley | | Granite | 46 36 46 N | 113 25 46 W |
| Sonyok Mountain | Summit | 1679 | Sanders | 47 22 26 N | 114 24 12 W |
| Soo | Locale | 769 | Roosevelt | 48 33 47 N | 104 58 24 W |
| Soo Prong | Stream | | Richland | 48 05 21 N | 104 53 06 W |
| Soo School (historical) | School | 769 | Roosevelt | 48 33 47 N | 104 58 24 W |
| Sophie Creek | Stream | | Lincoln | 48 58 23 N | 115 10 30 W |
| Sophie Lake | Lake | 767 | Lincoln | 48 57 50 N | 115 06 58 W |
| Sophie Lake Fishing Access Site | Locale | 767 | Lincoln | 48 57 27 N | 115 07 27 W |
| Sophie lake Recreation Site | Locale | 794 | Lincoln | 48 57 19 N | 115 07 43 W |
| Sorensen Ranch | Locale | 1816 | Madison | 45 13 19 N | 112 26 03 W |
| Sorenson Airport | Airport | 876 | Hill | 48 31 14 N | 110 06 50 W |
| Sorenson Dam | Dam | 690 | Sheridan | 48 43 48 N | 104 17 02 W |
| Soroptimist Park | Park | 924 | Flathead | 48 25 13 N | 114 20 48 W |
| Soroptomist Park | Park | 1465 | Gallatin | 45 40 50 N | 111 01 56 W |
| Sorrel Gulch | Valley | | Sanders | 47 51 00 N | 115 47 37 W |
| Sorrel Horse Creek | Stream | | Big Horn | 46 00 59 N | 107 30 58 W |
| Sorrel Horse School (historical) | School | 851 | Big Horn | 45 58 56 N | 107 32 02 W |
| Sorrell Guest Resort | Locale | 1527 | Teton | 47 38 27 N | 112 50 59 W |
| Sorrell Reservoir | Reservoir | 849 | Phillips | 47 45 47 N | 108 10 53 W |
| Sortorstorm's Ranch | Locale | 837 | Blaine | 48 42 55 N | 108 58 35 W |
| Soudan | Populated Place | 936 | Missoula | 47 01 35 N | 114 24 03 W |
| Soufly Reservoir | Reservoir | 732 | Valley | 47 51 18 N | 106 54 22 W |
| Souhrada School (historical) | School | 818 | Prairie | 46 53 48 N | 105 30 27 W |
| Soup Creek | Stream | | Lake | 47 50 13 N | 113 50 38 W |
| Soup Creek | Stream | | Lewis and Clark | 46 43 30 N | 111 48 49 W |
| Soup Creek Campground | Locale | 1115 | Lake | 47 48 38 N | 113 46 20 W |
| Sour Apple Dam | Dam | 909 | Chouteau | 47 54 54 N | 110 53 51 W |
| Sour Dough Flat (historical) | Populated Place | 1129 | Blaine | 47 59 58 N | 109 22 31 W |
| Sour Dough Hill Ski Trail | Trail | 2326 | Meagher | 46 50 19 N | 110 42 32 W |
| Sourdough | Populated Place | 1421 | Sweet Grass | 45 54 07 N | 109 48 52 W |
| Sourdough (historical) | Locale | 2048 | Jefferson | 46 16 60 N | 111 57 40 W |
| Sourdough Creek | Stream | | Beaverhead | 44 43 52 N | 112 52 28 W |
| Sourdough Creek | Stream | | Fergus | 47 33 31 N | 108 54 43 W |
| Sourdough Creek | Stream | | Jefferson | 46 16 25 N | 111 58 30 W |
| Sourdough Creek | Stream | | Lewis and Clark | 47 09 09 N | 112 45 23 W |
| Sourdough Creek | Stream | | Meagher | 46 34 01 N | 110 31 08 W |
| Sourdough Creek | Stream | | Meagher | 46 22 18 N | 110 40 56 W |
| Sourdough Creek | Stream | | Sweet Grass | 45 58 08 N | 109 45 04 W |
| Sourdough Creek Fishing Access Site | Locale | 1676 | Gallatin | 45 35 12 N | 111 01 23 W |
| Sourdough Flats | Swamp | 1543 | Lewis and Clark | 47 11 30 N | 112 54 53 W |
| Sourdough Island | Island | 1198 | Missoula | 47 06 15 N | 113 24 39 W |
| Sourdough Island on Salmon Lake Heliport | Airport | 1397 | Missoula | 47 05 59 N | 113 25 06 W |
| Sourdough Lake | Lake | 2910 | Park | 45 06 54 N | 109 58 07 W |
| Sourdough Mine | Mine | 1988 | Jefferson | 46 17 04 N | 111 57 43 W |
| Sourdough Mine | Mine | 2048 | Jefferson | 46 16 60 N | 111 57 40 W |
| Sourdough Peak | Summit | 2917 | Beaverhead | 44 41 11 N | 112 55 59 W |
| Sourdough Point | Cape | 2602 | Beaverhead | 44 46 49 N | 112 54 19 W |
| Sourdough School (historical) | School | 1369 | Sweet Grass | 45 57 34 N | 109 44 18 W |
| Sourdough Spring | Spring | 2585 | Beaverhead | 44 47 26 N | 112 53 19 W |
| Sourdough Spring | Spring | 1001 | Fergus | 47 34 42 N | 109 08 08 W |
| Souse Creek | Stream | | Lincoln | 48 25 09 N | 115 18 40 W |
| Souse Ridge | Ridge | 1110 | Lincoln | 48 24 36 N | 115 20 02 W |
| South Amelong Creek | Stream | | Sweet Grass | 46 02 04 N | 110 09 29 W |
| South America Park | Flat | 1992 | Powell | 46 22 42 N | 112 53 42 W |
| South Arm Sand Arroyo Bay | Bay | 685 | McCone | 47 48 24 N | 106 15 03 W |
| South Avenue Community Church | Church | 957 | Missoula | 46 50 58 N | 114 04 31 W |
| South Axolotl Lake Dam | Dam | 2263 | Madison | 45 13 30 N | 111 52 33 W |
| South Badger Creek | Stream | | Pondera | 48 14 35 N | 113 05 46 W |
| South Baldy Mountain | Summit | 3077 | Madison | 45 28 16 N | 111 54 56 W |
| South Bear Creek | Stream | | Treasure | 46 04 20 N | 107 07 01 W |
| South Bear Lake | Lake | 2243 | Ravalli | 46 22 16 N | 114 24 34 W |
| South Beaver Dam Creek | Stream | | Carter | 45 16 25 N | 104 04 42 W |
| South Beaver Reservoir | Reservoir | 689 | Valley | 48 01 14 N | 106 57 17 W |
| South Beaver Reservoir Dam | Dam | 689 | Valley | 48 01 12 N | 106 57 14 W |
| South Bench | Bench | 1601 | Fergus | 46 48 23 N | 109 03 57 W |
| South Bench School (historical) | School | 752 | Phillips | 48 11 23 N | 107 52 25 W |
| South Bench School (historical) | School | 739 | Valley | 48 16 56 N | 107 01 57 W |
| South Big Horn Creek | Stream | | Blaine | 47 57 03 N | 108 38 22 W |
| South Bootlegger Campground | Locale | 916 | Toole | 48 19 54 N | 111 18 33 W |
| South Bootlegger Picnic Area | Park | 916 | Toole | 48 19 54 N | 111 18 33 W |
| South Boulder Cemetery | Cemetery | 1419 | Madison | 45 49 01 N | 111 56 20 W |
| South Boulder Creek | Stream | | Granite | 46 26 29 N | 113 12 52 W |
| South Boulder River | Stream | | Madison | 45 50 36 N | 111 55 07 W |
| South Boundary Ski Trail | Trail | 1863 | Gallatin | 45 49 02 N | 110 53 48 W |
| South Boundary Trail | Trail | 1024 | Flathead | 48 30 12 N | 113 56 01 W |
| South Branch Big Beaver Creek | Stream | | Sanders | 47 40 34 N | 115 39 29 W |
| South Branch Big Swamp Creek | Stream | | Beaverhead | 45 26 08 N | 113 27 38 W |
| South Branch Coulee | Valley | | Roosevelt | 48 16 45 N | 104 46 47 W |
| South Branch Marten Creek | Stream | | Sanders | 47 53 05 N | 115 52 47 W |
| South Branch Miner Creek | Stream | | Beaverhead | 45 24 52 N | 113 26 58 W |
| South Branch Peoples Creek | Stream | | Blaine | 48 12 19 N | 109 21 28 W |
| South Branch Slater Creek | Stream | | Big Horn | 44 58 01 N | 107 08 01 W |
| South Branch West Fork Trout Creek | Stream | | Sanders | 47 47 17 N | 115 47 33 W |
| South Branch White Bear Creek | Stream | | Blaine | 48 20 53 N | 108 45 15 W |
| South Branch Whitman Coulee | Valley | | Big Horn | 45 46 15 N | 107 42 11 W |
| South Brandenburg School (historical) | School | 871 | Rosebud | 45 42 58 N | 106 17 52 W |