Area of Montana Counties
This table gives the total area, land area, and water area of Montana's counties.
The total area was calculated based on coordinates of county boundaries provided by the Montana Department of Administration (http://nris.mt.gov/nsdi/nris/county_gcdb.html). The coordinates were converted to a coordinate system based on Alber's Equal Area Projection to ensure that areas were calculated accurately.
For some applications, the land area of a county is more important to know than the total area. The second group of columns shows the land area of each county and the county's rank in land area. This was figured by calculating the water area of each county shown in the U.S. Census Bureau's TIGER files and subtracting the water area from the land area. The water area of each county and the county's rank in water area are shown in the third group of columns.
| | Total Area,
Square Miles | Land Area,
Square Miles | Water Area,
Square Miles |
| Montana | 147,040 | 145,470 | 1,570 |
| County | | Total Area,
Square Miles | Rank | | Land Area,
Square Miles | Rank | | Water Area,
Square Miles | Rank |
| Beaverhead | | 5573.2 | 1 | | 5543.2 | 1 | | 30.0 | 13 |
| Flathead | | 5255.5 | 2 | | 5097.9 | 3 | | 157.6 | 3 |
| Phillips | | 5211.7 | 3 | | 5122.6 | 2 | | 89.1 | 5 |
| Valley | | 5061.7 | 4 | | 4919.3 | 6 | | 142.3 | 4 |
| Rosebud | | 5025.4 | 5 | | 5009.5 | 4 | | 15.8 | 28 |
| Big Horn | | 5016.3 | 6 | | 4996.4 | 5 | | 19.9 | 24 |
| Garfield | | 4849.2 | 7 | | 4668.4 | 7 | | 180.7 | 1 |
| Fergus | | 4350.4 | 8 | | 4335.1 | 8 | | 15.3 | 30 |
| Blaine | | 4238.6 | 9 | | 4217.7 | 9 | | 21.0 | 21 |
| Chouteau | | 3996.7 | 10 | | 3965.4 | 10 | | 31.3 | 12 |
| Custer | | 3793.0 | 11 | | 3782.6 | 11 | | 10.4 | 35 |
| Lincoln | | 3675.1 | 12 | | 3619.4 | 12 | | 55.7 | 6 |
| Madison | | 3603.4 | 13 | | 3587.1 | 13 | | 16.4 | 27 |
| Lewis & Clark | | 3497.9 | 14 | | 3460.5 | 14 | | 37.4 | 10 |
| Carter | | 3348.1 | 15 | | 3339.0 | 15 | | 9.2 | 38 |
| Powder River | | 3298.8 | 16 | | 3297.9 | 16 | | 0.9 | 54 |
| Glacier | | 3035.8 | 17 | | 2990.9 | 17 | | 44.9 | 8 |
| Hill | | 2916.5 | 18 | | 2894.9 | 18 | | 21.6 | 19 |
| Park | | 2813.3 | 19 | | 2802.4 | 19 | | 11.0 | 34 |
| Sanders | | 2790.0 | 20 | | 2761.8 | 20 | | 28.2 | 15 |
| Cascade | | 2711.4 | 21 | | 2687.8 | 21 | | 23.6 | 18 |
| McCone | | 2682.1 | 22 | | 2641.3 | 22 | | 40.7 | 9 |
| Yellowstone | | 2648.8 | 23 | | 2634.6 | 23 | | 14.2 | 31 |
| Gallatin | | 2634.0 | 24 | | 2607.8 | 24 | | 26.2 | 16 |
| Missoula | | 2618.1 | 25 | | 2597.7 | 25 | | 20.5 | 22 |
| Ravalli | | 2400.5 | 26 | | 2394.2 | 26 | | 6.3 | 41 |
| Meagher | | 2394.7 | 27 | | 2391.7 | 27 | | 3.0 | 48 |
| Dawson | | 2383.5 | 28 | | 2373.4 | 28 | | 10.1 | 37 |
| Roosevelt | | 2368.3 | 29 | | 2354.1 | 29 | | 14.2 | 32 |
| Powell | | 2332.7 | 30 | | 2325.5 | 30 | | 7.2 | 39 |
| Teton | | 2292.0 | 31 | | 2270.6 | 31 | | 21.4 | 20 |
| Richland | | 2104.1 | 32 | | 2084.2 | 32 | | 19.8 | 25 |
| Carbon | | 2061.6 | 33 | | 2047.4 | 33 | | 14.2 | 33 |
| Toole | | 1944.6 | 34 | | 1916.3 | 34 | | 28.3 | 14 |
| Musselshell | | 1871.5 | 35 | | 1865.8 | 36 | | 5.7 | 43 |
| Judith Basin | | 1870.5 | 36 | | 1869.5 | 35 | | 1.0 | 52 |
| Sweet Grass | | 1862.2 | 37 | | 1855.2 | 37 | | 7.1 | 40 |
| Stillwater | | 1806.7 | 38 | | 1789.5 | 38 | | 17.2 | 26 |
| Prairie | | 1742.3 | 39 | | 1736.1 | 39 | | 6.2 | 42 |
| Granite | | 1732.8 | 40 | | 1727.2 | 40 | | 5.7 | 44 |
| Sheridan | | 1704.2 | 41 | | 1669.0 | 41 | | 35.2 | 11 |
| Petroleum | | 1674.5 | 42 | | 1650.6 | 43 | | 23.9 | 17 |
| Jefferson | | 1659.3 | 43 | | 1657.1 | 42 | | 2.3 | 51 |
| Lake | | 1653.8 | 44 | | 1493.4 | 46 | | 160.4 | 2 |
| Pondera | | 1641.6 | 45 | | 1625.9 | 44 | | 15.7 | 29 |
| Fallon | | 1622.5 | 46 | | 1619.5 | 45 | | 2.9 | 49 |
| Liberty | | 1447.1 | 47 | | 1427.0 | 47 | | 20.1 | 23 |
| Wheatland | | 1427.5 | 48 | | 1422.0 | 49 | | 5.5 | 45 |
| Daniels | | 1426.5 | 49 | | 1425.8 | 48 | | 0.7 | 56 |
| Broadwater | | 1237.9 | 50 | | 1189.1 | 51 | | 48.8 | 7 |
| Mineral | | 1223.4 | 51 | | 1220.0 | 50 | | 3.5 | 47 |
| Golden Valley | | 1175.3 | 52 | | 1172.9 | 52 | | 2.5 | 50 |
| Treasure | | 984.5 | 53 | | 978.9 | 53 | | 5.5 | 46 |
| Wibaux | | 889.1 | 54 | | 888.3 | 54 | | 0.8 | 55 |
| Deer Lodge | | 741.2 | 55 | | 731.0 | 55 | | 10.2 | 36 |
| Silver Bow | | 718.6 | 56 | | 717.6 | 56 | | 1.0 | 53 |
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