Data / Rankings / Population / Counties in Idaho

Counties in Idaho by population

Ada County had the highest population of 44 counties in 2021, at 513,092. Clark County had the lowest, at 794. The median was 14,140 and the figure for Idaho was 1.9 million. Source: the U.S. Census Bureau.

Highest513,092Ada County
Lowest794Clark County
Median14,14044 counties
Idaho1,904,855History

All counties, 2021

CSVChart (SVG)

Ada CountyAda County: 513,092 persons513,092Canyon CountyCanyon County: 243,711 persons243,711Kootenai CountyKootenai County: 180,104 persons180,104Bonneville CountyBonneville County: 128,072 persons128,072Twin Falls CountyTwin Falls County: 92,382 persons92,382Bannock CountyBannock County: 88,605 persons88,605Madison CountyMadison County: 54,126 persons54,126Bonner CountyBonner County: 49,639 persons49,639Bingham CountyBingham County: 48,932 persons48,932Nez Perce CountyNez Perce County: 42,515 persons42,515Latah CountyLatah County: 40,403 persons40,403Jefferson CountyJefferson County: 32,207 persons32,207Elmore CountyElmore County: 28,985 persons28,985Payette CountyPayette County: 26,380 persons26,380Cassia CountyCassia County: 25,235 persons25,235Blaine CountyBlaine County: 24,784 persons24,784Jerome CountyJerome County: 24,741 persons24,741Minidoka CountyMinidoka County: 21,951 persons21,951Gem CountyGem County: 19,802 persons19,802Idaho CountyIdaho County: 17,060 persons17,060Gooding CountyGooding County: 15,800 persons15,800Franklin CountyFranklin County: 14,675 persons14,675Shoshone CountyShoshone County: 13,604 persons13,604Fremont CountyFremont County: 13,585 persons13,585Boundary CountyBoundary County: 12,621 persons12,621Owyhee CountyOwyhee County: 12,360 persons12,360Teton CountyTeton County: 12,276 persons12,276Valley CountyValley County: 12,252 persons12,252Washington CountyWashington County: 10,902 persons10,902Benewah CountyBenewah County: 9,896 persons9,896Clearwater CountyClearwater County: 8,934 persons8,934Lemhi CountyLemhi County: 8,160 persons8,160Boise CountyBoise County: 8,146 persons8,146Power CountyPower County: 7,982 persons7,982Caribou CountyCaribou County: 7,113 persons7,113Bear Lake CountyBear Lake County: 6,567 persons6,567Lincoln CountyLincoln County: 5,291 persons5,291Adams CountyAdams County: 4,619 persons4,619Oneida CountyOneida County: 4,604 persons4,604Custer CountyCuster County: 4,445 persons4,445Lewis CountyLewis County: 3,704 persons3,704Butte CountyButte County: 2,664 persons2,664Camas CountyCamas County: 1,135 persons1,135Clark CountyClark County: 794 persons794
persons. Source: U.S. Census Bureau. Retrieved 2026-10-08.

Full ranking

RankCounties2021
persons		Change on 2020
1Ada County513,092+3%
2Canyon County243,711+4.6%
3Kootenai County180,104+4.2%
4Bonneville County128,072+2.7%
5Twin Falls County92,382+2.2%
6Bannock County88,605+1.5%
7Madison County54,126+2.2%
8Bonner County49,639+4.7%
9Bingham County48,932+1.7%
10Nez Perce County42,515+0.9%
11Latah County40,403+1.9%
12Jefferson County32,207+3.6%
13Elmore County28,985+1.1%
14Payette County26,380+3.1%
15Cassia County25,235+1.9%
16Blaine County24,784+1.8%
17Jerome County24,741+1.9%
18Minidoka County21,951+1.3%
19Gem County19,802+2.7%
20Idaho County17,060+2.8%
21Gooding County15,800+1%
22Franklin County14,675+2.7%
23Shoshone County13,604+3.1%
24Fremont County13,585+1.2%
25Boundary County12,621+4%
26Owyhee County12,360+3.1%
27Teton County12,276+4.6%
28Valley County12,252+3.5%
29Washington County10,902+3.3%
30Benewah County9,896+3.3%
31Clearwater County8,934+2%
32Lemhi County8,160+2.6%
33Boise County8,146+6.3%
34Power County7,982+1.3%
35Caribou County7,113+1.4%
36Bear Lake County6,567+3.2%
37Lincoln County5,291+3%
38Adams County4,619+4.4%
39Oneida County4,604+0.9%
40Custer County4,445+4.1%
41Lewis County3,704+4.8%
42Butte County2,664+3.2%
43Camas County1,135+5%
44Clark County794+0.4%

Other periods

About this ranking

Resident population. Spain and the EU: 1 January, with Spanish figures from the official municipal register (Padrón). United States: Census Bureau population estimates for 1 July. Other countries and the World: World Bank mid-year estimates, which count all residents regardless of legal status or citizenship.

For Denmark, Statistics Denmark counts the registered resident population on 1 January. Greenland and the Faroe Islands are excluded. The annual series selects the first-quarter reference date from FOLK1A. The World Bank series exists for every country, so use it (through compare) to rank countries on one basis.

Every value in the ranking comes from the same publisher and the same period, so the counties are compared on one definition. Equal values share a rank.

How to cite

U.S. Census Bureau. Annual estimates of the resident population for the United States, states and counties, 1 July (Population Estimates Program). https://www2.census.gov/programs-surveys/popest/datasets/2020-2025/. Retrieved 2026-10-08.

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Questions

Which county has the highest population?

Ada County, with 513,092 in 2021, according to the U.S. Census Bureau.

Which county has the lowest population?

Clark County, with 794 in 2021.

Where does this ranking come from?

Every value comes from one source and one period, so the places are comparable: U.S. Census Bureau, Annual estimates of the resident population for the United States, states and counties, 1 July (Population Estimates Program). Retrieved 2026-10-08.

Population: other rankings

Counties in Idaho: more rankings