Data / Rankings / Population aged 65 and over / Counties in Idaho

Counties in Idaho by share of population aged 65 and over

Lemhi County had the highest share of population aged 65 and over of 44 counties in 2020, at 31.2%. Madison County had the lowest, at 6.2%. The median was 19.3% and the figure for Idaho was 16.9%. Source: the U.S. Census Bureau.

Highest31.2Lemhi County
Lowest6.2Madison County
Median19.344 counties
Idaho16.9History

All counties, 2020

CSVChart (SVG)

Lemhi CountyLemhi County: 31.2 %31.2Adams CountyAdams County: 30.7 %30.7Custer CountyCuster County: 30.3 %30.3Idaho CountyIdaho County: 29.6 %29.6Clearwater CountyClearwater County: 28.9 %28.9Boise CountyBoise County: 27 %27Valley CountyValley County: 26.6 %26.6Bonner CountyBonner County: 26.5 %26.5Lewis CountyLewis County: 26.1 %26.1Washington CountyWashington County: 26.1 %26.1Boundary CountyBoundary County: 25.9 %25.9Shoshone CountyShoshone County: 25.5 %25.5Benewah CountyBenewah County: 25.4 %25.4Camas CountyCamas County: 24.3 %24.3Gem CountyGem County: 23.2 %23.2Butte CountyButte County: 22.4 %22.4Blaine CountyBlaine County: 22 %22Bear Lake CountyBear Lake County: 21.6 %21.6Nez Perce CountyNez Perce County: 21.2 %21.2Oneida CountyOneida County: 20.7 %20.7Kootenai CountyKootenai County: 20.7 %20.7Payette CountyPayette County: 19.7 %19.7Clark CountyClark County: 18.8 %18.8Fremont CountyFremont County: 18.3 %18.3Gooding CountyGooding County: 17.9 %17.9Caribou CountyCaribou County: 17.8 %17.8Owyhee CountyOwyhee County: 17.8 %17.8Twin Falls CountyTwin Falls County: 16.6 %16.6Lincoln CountyLincoln County: 16.5 %16.5Power CountyPower County: 16.5 %16.5Minidoka CountyMinidoka County: 16 %16Ada CountyAda County: 15.7 %15.7Bannock CountyBannock County: 15.4 %15.4Franklin CountyFranklin County: 15.3 %15.3Cassia CountyCassia County: 15.2 %15.2Bingham CountyBingham County: 15 %15Canyon CountyCanyon County: 14.9 %14.9Latah CountyLatah County: 14.8 %14.8Elmore CountyElmore County: 14 %14Jerome CountyJerome County: 13.8 %13.8Bonneville CountyBonneville County: 13.8 %13.8Teton CountyTeton County: 13.1 %13.1Jefferson CountyJefferson County: 12.3 %12.3Madison CountyMadison County: 6.2 %6.2
%. Source: Invokely calculation with data from U.S. Census Bureau. Retrieved 2026-10-09.

Full ranking

RankCounties2020 (%)
1Lemhi County31.2
2Adams County30.7
3Custer County30.3
4Idaho County29.6
5Clearwater County28.9
6Boise County27
7Valley County26.6
8Bonner County26.5
9Lewis County26.1
10Washington County26.1
11Boundary County25.9
12Shoshone County25.5
13Benewah County25.4
14Camas County24.3
15Gem County23.2
16Butte County22.4
17Blaine County22
18Bear Lake County21.6
19Nez Perce County21.2
20Oneida County20.7
21Kootenai County20.7
22Payette County19.7
23Clark County18.8
24Fremont County18.3
25Gooding County17.9
26Caribou County17.8
27Owyhee County17.8
28Twin Falls County16.6
29Lincoln County16.5
30Power County16.5
31Minidoka County16
32Ada County15.7
33Bannock County15.4
34Franklin County15.3
35Cassia County15.2
36Bingham County15
37Canyon County14.9
38Latah County14.8
39Elmore County14
40Jerome County13.8
41Bonneville County13.8
42Teton County13.1
43Jefferson County12.3
44Madison County6.2

Other periods

About this ranking

Residents aged 65 or over as a percentage of total population. Spain: 1 January, INE annual census. United States: 1 July, Census Bureau population estimates. World Bank figures for other countries and the World refer to mid-year.

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. Population Estimates Program, county population by age and sex (cc-est agesex): residents aged 65 and over as a percentage of the total, 1 July; states and the nation summed from counties. https://www2.census.gov/programs-surveys/popest/datasets/2020-2025/counties/asrh/cc-est2025-agesex-all.csv. Retrieved 2026-10-09.

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Rank Counties in Idaho by share of population aged 65 and over using official data, and cite the source.
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Questions

Which county has the highest share of population aged 65 and over?

Lemhi County, with 31.2% in 2020, according to the U.S. Census Bureau.

Which county has the lowest share of population aged 65 and over?

Madison County, with 6.2% in 2020.

Where does this ranking come from?

Every value comes from one source and one period, so the places are comparable: U.S. Census Bureau, Population Estimates Program, county population by age and sex (cc-est agesex): residents aged 65 and over as a percentage of the total, 1 July; states and the nation summed from counties. Retrieved 2026-10-09.

Population aged 65 and over: other rankings

Counties in Idaho: more rankings