Montana Voting-age Population By County in 2021 (ACS-5Yrs)

Updated on February 28, 2025.

Based on the US Census ACS-5Yrs estimates, in 2021, the voting-age population of Montana was 845.16K which was 78.40% of the total Montana population. Among all Montana counties, Yellowstone had the highest voting-age population (125.03K), followed by Missoula (95.40K), and Gallatin (93.62K).

On the other hand, the counties with the least voting-age population were: Petroleum (358), Treasure (576), and Golden Valley (683).

The chart and table below shows the voting-age population of each county and the percentage of each county's population that are of voting-age.

You can see similar information for other states and by state for the United States.

Montana Voting-age Population By County in 2021
Montana Voting-age Population By County in 2021
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County Voting-age Population % of County Population
Beaverhead 7780 82.85
Big Horn 8716 66.04
Blaine 4917 69.74
Broadwater 5371 80.88
Carbon 8621 82.20
Carter 1113 82.51
Cascade 65010 77.23
Chouteau 4524 76.73
Custer 9545 79.75
Daniels 1371 78.84
Dawson 7114 79.02
Deer Lodge 8109 86.45
Fallon 2313 75.24
Fergus 9163 79.93
Flathead 80727 78.07
Gallatin 93617 80.20
Garfield 761 78.29
Glacier 9705 70.19
Golden Valley 683 83.29
Granite 2737 82.12
Hill 11719 71.91
Jefferson 9587 79.51
Judith Basin 1534 76.55
Lake 23777 76.63
Lewis and Clark 55171 78.44
Liberty 1496 73.84
Lincoln 16061 81.64
McCone 1464 81.11
Madison 7173 84.40
Meagher 1594 82.51
Mineral 3621 80.65
Missoula 95397 81.27
Musselshell 3896 80.95
Park 14136 82.80
Petroleum 358 82.49
Phillips 3229 76.28
Pondera 4561 76.35
Powder River 1400 79.59
Powell 5902 84.86
Prairie 937 76.36
Ravalli 35428 80.90
Richland 8472 74.48
Roosevelt 7177 65.94
Rosebud 6096 72.02
Sanders 10134 82.40
Sheridan 2794 79.33
Silver Bow 27789 79.36
Stillwater 6994 78.44
Sweet Grass 2935 79.54
Teton 4645 75.25
Toole 4003 79.85
Treasure 576 83.12
Valley 5781 76.54
Wheatland 1648 79.16
Wibaux 751 73.77
Yellowstone 125030 76.43