Feature Name | Class | Elev. meters | County | Latitude DMS | Longitude DMS |
| Alton Bench | Bench | 1115 | Fergus | 47 23 14 N | 109 53 23 W |
| Alton Mine | Mine | 656 | Roosevelt | 48 10 00 N | 104 46 15 W |
| Alton Post Office (historical) | Post Office | 1114 | Fergus | 47 28 10 N | 109 49 52 W |
| Alton School (historical) | School | 1100 | Fergus | 47 23 19 N | 109 51 38 W |
| Altoona Lakes | Lake | 2327 | Granite | 46 23 49 N | 113 05 40 W |
| Altoona Lakes Mine | Mine | 2336 | Granite | 46 23 48 N | 113 05 46 W |
| Alturas Number One Mountain | Summit | 3067 | Beaverhead | 45 22 38 N | 113 01 31 W |
| Alturas Number Two Mountain | Summit | 3191 | Beaverhead | 45 23 39 N | 113 00 34 W |
| Altyn (historical) | Populated Place | 1461 | Glacier | 48 47 60 N | 113 37 28 W |
| Altyn Peak | Summit | 2419 | Glacier | 48 48 48 N | 113 39 22 W |
| Altyn Post Office (historical) | Post Office | 1461 | Glacier | 48 47 60 N | 113 37 28 W |
| Aluminum Dam | Dam | 659 | Wibaux | 47 21 54 N | 104 10 02 W |
| Alumni Field | Park | 1745 | Silver Bow | 46 00 42 N | 112 33 38 W |
| Alumni Park | Park | 639 | Valley | 48 11 56 N | 106 38 15 W |
| Alvord Lake | Lake | 787 | Lincoln | 48 29 43 N | 115 53 09 W |
| Alzada | Populated Place | 1050 | Carter | 45 01 23 N | 104 24 45 W |
| Alzada Baptist Church | Church | 1047 | Carter | 45 01 40 N | 104 24 60 W |
| Alzada Cemetery | Cemetery | 1047 | Carter | 45 02 03 N | 104 25 08 W |
| Alzada Congregational Church | Church | 1048 | Carter | 45 01 27 N | 104 24 59 W |
| Alzada Mission | Church | 1048 | Carter | 45 01 27 N | 104 24 59 W |
| Alzada Post Office | Post Office | 1050 | Carter | 45 01 23 N | 104 24 54 W |
| Alzada School | School | 1050 | Carter | 45 01 15 N | 104 24 47 W |
| Amador (historical) | Locale | 845 | Mineral | 47 10 34 N | 114 52 11 W |
| Amador (historical) | Populated Place | 845 | Mineral | 47 10 34 N | 114 52 11 W |
| Amador Mine | Mine | 1122 | Mineral | 47 06 51 N | 115 00 33 W |
| Amador Mine | Mine | 1442 | Mineral | 47 06 50 N | 115 01 33 W |
| Amador School (historical) | School | 845 | Mineral | 47 10 34 N | 114 52 11 W |
| Amalgamated (historical) | Locale | 1526 | Carbon | 45 09 51 N | 109 12 48 W |
| Amaranth/Robert Burns Mine | Mine | 1935 | Beaverhead | 45 16 42 N | 112 52 20 W |
| Amazon | Populated Place | 1663 | Jefferson | 46 19 13 N | 112 06 26 W |
| Amazon (historical) | Locale | 1663 | Jefferson | 46 19 13 N | 112 06 26 W |
| Amazon Creek | Stream | | Jefferson | 46 15 40 N | 112 05 26 W |
| Amazon Post Office (historical) | Post Office | 1663 | Jefferson | 46 19 13 N | 112 06 26 W |
| Ambassador Mine | Mine | 1146 | Sanders | 47 46 31 N | 115 41 60 W |
| Ambassador RV Park | Locale | 2032 | Gallatin | 44 39 35 N | 111 06 23 W |
| Ambassador/Lulu Mine | Mine | 1134 | Sanders | 47 46 30 N | 115 41 60 W |
| Amber Butte | Summit | 2684 | Gallatin | 45 24 60 N | 111 02 03 W |
| Ambrose Creek | Stream | | Ravalli | 46 33 54 N | 114 02 13 W |
| Ambrose Saddle | Gap | 1795 | Ravalli | 46 30 60 N | 113 50 57 W |
| Ambush Meadows Ski Trail | Trail | 2365 | Madison | 45 16 51 N | 111 24 24 W |
| Ambush Ski Trail | Trail | 2365 | Madison | 45 16 51 N | 111 24 24 W |
| Amelia Island Fishing Access Site | Locale | 799 | Treasure | 46 18 58 N | 107 13 35 W |
| Amelong Creek | Stream | | Sweet Grass | 46 01 23 N | 110 08 30 W |
| American Baptist - Methodist Church | Church | 1088 | Ravalli | 46 14 54 N | 114 09 49 W |
| American Bar | Bar | 1113 | Lewis and Clark | 46 48 56 N | 111 56 03 W |
| American Bar Gulch | Valley | | Lewis and Clark | 46 48 29 N | 111 56 11 W |
| American Computer Museum | Building | 1470 | Gallatin | 45 40 43 N | 111 02 27 W |
| American Creek | Stream | | Deer Lodge | 45 58 40 N | 113 01 40 W |
| American Creek | Stream | | Lincoln | 49 02 60 N | 116 00 05 W |
| American Fork | Stream | | Wheatland | 46 24 40 N | 109 43 27 W |
| American Fork Ranch | Locale | 1708 | Wheatland | 46 13 39 N | 110 07 45 W |
| American Fork Ranch Ditch | Canal | 1759 | Sweet Grass | 46 12 47 N | 110 07 58 W |
| American Gold Mine | Mine | 1451 | Mineral | 47 04 06 N | 115 02 14 W |
| American Gulch | Valley | | Lewis and Clark | 46 41 51 N | 112 21 01 W |
| American Gulch | Valley | | Powell | 46 46 10 N | 112 39 10 W |
| American Gulch | Valley | | Silver Bow | 45 58 58 N | 112 50 39 W |
| American Gulch | Valley | | Silver Bow | 46 08 54 N | 112 33 29 W |
| American Gulch (historical) | Locale | 1539 | Powell | 46 46 10 N | 112 39 08 W |
| American Gulch Spring | Spring | 1899 | Lewis and Clark | 46 42 55 N | 112 19 34 W |
| American Kootenai Mine | Mine | 1211 | Lincoln | 48 03 01 N | 115 32 39 W |
| American Kootenai Mine | Mine | 1173 | Lincoln | 48 03 03 N | 115 32 52 W |
| American Legion Park | Park | 1844 | Beaverhead | 45 37 05 N | 113 27 03 W |
| American Legion Park | Park | 794 | Hill | 48 32 38 N | 109 40 03 W |
| American Legion Park | Park | 1089 | Ravalli | 46 14 42 N | 114 09 28 W |
| American Legion Park | Park | 596 | Roosevelt | 48 07 04 N | 105 12 04 W |
| American Lutheran Church | Church | 721 | Blaine | 48 31 60 N | 108 47 03 W |
| American Lutheran Church | Church | 742 | Blaine | 48 35 24 N | 109 13 48 W |
| American Lutheran Church | Church | 906 | Fallon | 46 21 46 N | 104 16 52 W |
| American Lutheran Church | Church | 994 | Fergus | 47 33 28 N | 109 22 38 W |
| American Lutheran Church | Church | 1062 | Fergus | 47 01 27 N | 108 48 20 W |
| American Lutheran Church | Church | 1563 | Meagher | 46 32 47 N | 110 53 44 W |
| American Lutheran Church | Church | 1369 | Park | 45 39 50 N | 110 33 11 W |
| American Lutheran Church | Church | 1285 | Wheatland | 46 26 11 N | 109 49 40 W |
| American Lutheran Church (historical) | Church | 652 | Dawson | 46 53 23 N | 104 55 59 W |
| American Lutheran Church of Richey | Church | 763 | Dawson | 47 38 36 N | 105 04 10 W |
| American Mine | Mine | 2119 | Deer Lodge | 46 14 20 N | 112 36 23 W |
| American Mine | Mine | 1625 | Judith Basin | 46 52 16 N | 110 20 41 W |
| American Mountain | Summit | 2006 | Lincoln | 48 57 42 N | 116 02 01 W |
| American Podiatry Clinic | Hospital | 1611 | Deer Lodge | 46 07 35 N | 112 57 07 W |
| Ames Creek | Stream | | Beaverhead | 45 19 37 N | 113 11 02 W |
| Amesville Post Office (historical) | Post Office | 1797 | Beaverhead | 45 00 36 N | 113 06 40 W |
| Amex Number 1 Mine | Mine | 1820 | Granite | 46 49 28 N | 113 20 07 W |
| Amex Number 5 Mine | Mine | 1855 | Granite | 46 49 38 N | 113 21 01 W |
| Amherst | Locale | 1104 | Fergus | 47 08 59 N | 109 37 30 W |
| Amherst | Populated Place | 1104 | Fergus | 47 08 59 N | 109 37 30 W |
| Amisk Pond | Lake | 1508 | Hill | 48 09 49 N | 109 40 04 W |
| Ammon Gulch | Valley | | Granite | 46 30 37 N | 113 42 37 W |
| Amo School (historical) | School | 781 | Dawson | 46 56 57 N | 105 01 37 W |
| Amos Post Office (historical) | Post Office | 905 | Hill | 48 48 23 N | 109 52 03 W |
| Amos School (historical) | School | 905 | Hill | 48 48 23 N | 109 52 03 W |
| Amphitheater Mountain | Summit | 2639 | Glacier | 48 35 59 N | 113 29 15 W |
| Amphitheater Tunnel Number 4 | Tunnel | 1029 | Chouteau | 47 33 06 N | 110 55 44 W |
| Amphitheatre Mountain | Summit | 2472 | Flathead | 47 38 39 N | 113 10 35 W |
| Ample/Hickey Mine | Mine | 2046 | Lewis and Clark | 46 44 08 N | 112 19 50 W |
| Ampo Ditch | Canal | 1930 | Deer Lodge | 45 51 59 N | 113 20 58 W |
| Ampo Toomey Ditch | Canal | 1843 | Deer Lodge | 45 49 51 N | 113 19 05 W |
| Amsterdam | Populated Place | 1355 | Gallatin | 45 45 29 N | 111 19 12 W |
| Amsterdam (historical) | Locale | 1355 | Gallatin | 45 45 29 N | 111 19 12 W |
| Amsterdam Elementary School | School | 1354 | Gallatin | 45 45 25 N | 111 19 13 W |
| Amy Lake | Lake | 909 | Flathead | 48 11 26 N | 114 05 33 W |
| AN Canal | Canal | 1111 | Pondera | 48 23 03 N | 112 08 11 W |
| AN Six Canal | Canal | 1119 | Pondera | 48 22 59 N | 112 15 05 W |
| AN Two Canal | Canal | 1140 | Pondera | 48 21 38 N | 112 15 08 W |
| Anaconda | Locale | 1608 | Deer Lodge | 46 07 54 N | 112 57 05 W |
| Anaconda | Populated Place | 1600 | Deer Lodge | 46 07 43 N | 112 56 32 W |
| Anaconda - Deer Lodge County Fire Department | Building | 1613 | Deer Lodge | 46 07 53 N | 112 57 28 W |
| Anaconda - Deer Lodge County Police Department | Building | 1632 | Deer Lodge | 46 07 23 N | 112 57 19 W |
| Anaconda Airport | Airport | 1528 | Deer Lodge | 46 08 58 N | 112 51 51 W |
| Anaconda Catholic Cemetery | Cemetery | 1549 | Deer Lodge | 46 06 60 N | 112 51 55 W |
| Anaconda Civilan Conservation Center | Locale | 1875 | Deer Lodge | 46 10 60 N | 113 07 55 W |