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

Updated on March 28, 2026.

Based on the US Census Bureau's special tabulation from the ACS 5-year estimates, in 2021, the citizen voting-age population for Idaho was 1,298,420 and represented 71.67% of the total Idaho population.

Among all Idaho counties, Ada had the highest citizen voting-age population (360.20K), followed by Canyon (153.54K), and Kootenai (128.25K).

In terms of percentages, Adams had the highest percentage of its population being citizens of voting-age (82.99%), followed by Valley (82.83%), and Custer (82.46%).

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

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

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Idaho Citizen Population By County in 2021

Data Source: US Census - ACS 5-Year (CVAP).

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Idaho Citizen Voting-age Population By County in 2021

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County	Citizen Voting-age Population	% of County Population
Ada	360195	74.23
Canyon	153540	67.53
Kootenai	128245	76.19
Bonneville	81610	67.02
Bannock	62470	72.34
Twin Falls	60575	67.96
Bonner	36865	79.31
Madison	36040	70.69
Nez Perce	32625	78.01
Bingham	31755	66.80
Latah	31025	78.61
Elmore	19750	69.55
Jefferson	19325	63.52
Payette	17320	69.47
Blaine	16400	68.71
Cassia	15130	61.83
Gem	14025	75.04
Jerome	13365	55.50
Minidoka	13255	61.95
Idaho	13190	79.96
Shoshone	10325	78.67
Gooding	9855	63.91
Valley	9505	82.83
Fremont	9485	70.94
Franklin	9345	66.58
Boundary	8905	74.43
Teton	8035	69.93
Owyhee	7965	67.41
Washington	7620	73.09
Benewah	7335	77.13
Clearwater	7180	82.34
Lemhi	6460	81.26
Boise	6220	82.38
Caribou	4835	69.02
Power	4735	60.28
Bear Lake	4515	71.38
Adams	3585	82.99
Custer	3525	82.46
Lincoln	3195	61.62
Oneida	3195	70.76
Lewis	2755	76.21
Butte	1905	73.98
Camas	725	69.38
Clark	495	58.93