Idaho Citizen Voting-age Population By County in 2018 (ACS-5Yrs)

Updated on March 28, 2026.

Based on the US Census Bureau's special tabulation from the ACS 5-year estimates, in 2018, the citizen voting-age population for Idaho was 1,192,740 and represented 70.67% of the total Idaho population.

Among all Idaho counties, Ada had the highest citizen voting-age population (325.75K), followed by Canyon (139.47K), and Kootenai (116.71K).

In terms of percentages, Clearwater had the highest percentage of its population being citizens of voting-age (82.41%), followed by Custer (82.13%), and Valley (81.64%).

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 2018

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

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Idaho Citizen Voting-age Population By County in 2018

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County	Citizen Voting-age Population	% of County Population
Ada	325745	73.03
Canyon	139465	65.71
Kootenai	116710	75.98
Bonneville	74360	66.16
Bannock	60530	71.16
Twin Falls	56305	67.30
Bonner	33790	79.11
Nez Perce	31225	77.76
Latah	30380	77.42
Bingham	29665	65.13
Madison	27215	70.31
Elmore	18420	69.68
Jefferson	17565	62.80
Payette	15715	68.21
Blaine	14925	67.86
Cassia	14040	59.45
Jerome	13205	56.36
Idaho	13040	79.83
Minidoka	12720	61.70
Gem	12690	74.43
Shoshone	9905	79.08
Gooding	9580	63.15
Fremont	9025	69.61
Boundary	8590	74.37
Franklin	8575	64.57
Valley	8490	81.64
Owyhee	7520	65.65
Teton	7510	67.78
Washington	7180	71.62
Clearwater	7120	82.41
Benewah	6915	76.11
Lemhi	6245	80.06
Boise	5820	81.23
Caribou	4735	68.43
Power	4720	61.18
Bear Lake	4305	72.23
Custer	3400	82.13
Adams	3260	81.10
Lincoln	3095	58.18
Oneida	2980	68.90
Lewis	2920	75.94
Butte	2005	77.11
Camas	655	74.01
Clark	480	44.65