Data / Rankings / Population aged 18 to 64 / Counties in Idaho

Counties in Idaho by population aged 18 to 64, 2025

Madison County had the highest population aged 18 to 64 of 44 counties in 2025, at 71.8%. Idaho County had the lowest, at 48%. The median was 54.6% and the figure for Idaho was 58.1%. Source: the U.S. Census Bureau.

Highest71.8Madison County
Lowest48Idaho County
Median54.644 counties
Idaho58.1History

All counties, 2025

Madison County: 71.8 %Madison County71.8Latah County: 63.5 %Latah County63.5Teton County: 63.1 %Teton County63.1Ada County: 61 %Ada County61Elmore County: 60 %Elmore County60Bannock County: 58.7 %Bannock County58.7Canyon County: 58.5 %Canyon County58.5Bonneville County: 56.9 %Bonneville County56.9Twin Falls County: 56.9 %Twin Falls County56.9Lincoln County: 56.8 %Lincoln County56.8Nez Perce County: 56.6 %Nez Perce County56.6Owyhee County: 56.6 %Owyhee County56.6Blaine County: 56.4 %Blaine County56.4Jerome County: 56.2 %Jerome County56.2Gooding County: 56.1 %Gooding County56.1Fremont County: 56 %Fremont County56Jefferson County: 55.9 %Jefferson County55.9Kootenai County: 55.7 %Kootenai County55.7Bingham County: 55.6 %Bingham County55.6Power County: 55.5 %Power County55.5Minidoka County: 55.1 %Minidoka County55.1Cassia County: 54.6 %Cassia County54.6Franklin County: 54.6 %Franklin County54.6Payette County: 54 %Payette County54Shoshone County: 53.7 %Shoshone County53.7Boise County: 53.4 %Boise County53.4Clearwater County: 53.2 %Clearwater County53.2Gem County: 53 %Gem County53Caribou County: 53 %Caribou County53Valley County: 52.9 %Valley County52.9Washington County: 52.6 %Washington County52.6Bonner County: 52.4 %Bonner County52.4Clark County: 52.2 %Clark County52.2Adams County: 51.4 %Adams County51.4Benewah County: 51.2 %Benewah County51.2Camas County: 51.1 %Camas County51.1Oneida County: 51 %Oneida County51Butte County: 50.9 %Butte County50.9Bear Lake County: 50.9 %Bear Lake County50.9Boundary County: 50.6 %Boundary County50.6Custer County: 50.2 %Custer County50.2Lewis County: 50 %Lewis County50Lemhi County: 49.6 %Lemhi County49.6Idaho County: 48 %Idaho County48
%. Source: Invokely calculation with data from U.S. Census Bureau. Retrieved 2026-10-12.

Full ranking

RankCounties2025 (%)Change on 2024
1Madison County71.8-0.1 pts
2Latah County63.5-0.4 pts
3Teton County63.1-0.1 pts
4Ada County61-0 pts
5Elmore County60-0.4 pts
6Bannock County58.7-0 pts
7Canyon County58.5+0.3 pts
8Bonneville County56.9+0.3 pts
9Twin Falls County56.9+0.2 pts
10Lincoln County56.80 pts
11Nez Perce County56.6-0.1 pts
12Owyhee County56.6+0.2 pts
13Blaine County56.4-0.1 pts
14Jerome County56.2-0.1 pts
15Gooding County56.1-0 pts
16Fremont County56-0.1 pts
17Jefferson County55.9+0.3 pts
18Kootenai County55.7-0.1 pts
19Bingham County55.6+0.1 pts
20Power County55.5+0.1 pts
21Minidoka County55.1-0.1 pts
22Cassia County54.6+0.4 pts
23Franklin County54.6+0.2 pts
24Payette County54+0.1 pts
25Shoshone County53.7-0.4 pts
26Boise County53.4-0.2 pts
27Clearwater County53.2-0.6 pts
28Gem County53-0.4 pts
29Caribou County53+0.3 pts
30Valley County52.9-0.2 pts
31Washington County52.6+0.2 pts
32Bonner County52.4-0.3 pts
33Clark County52.2-1.2 pts
34Adams County51.4-0.6 pts
35Benewah County51.2-0.3 pts
36Camas County51.1-0.5 pts
37Oneida County51-0.3 pts
38Butte County50.9-0.3 pts
39Bear Lake County50.90 pts
40Boundary County50.6-0.2 pts
41Custer County50.2-0.2 pts
42Lewis County50-1.1 pts
43Lemhi County49.60 pts
44Idaho County48-0.6 pts

Other periods

About this ranking

Residents aged 18 to 64 as a percentage of total population on 1 July. United States: Census Bureau county population estimates by age; states and the nation are sums of their counties.

Not comparable with working-age shares for ages 15 to 64 used in EU and World Bank statistics.

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: residents aged 18 to 64 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties. https://www.census.gov/programs-surveys/popest/data/data-sets.html. Retrieved 2026-10-12.

Citation styles

The publisher is the author. Invokely is named only as the place the figures were read, where a style asks for it.

APA 7

U.S. Census Bureau. (2026). Population Estimates Program, county population by age and sex: residents aged 18 to 64 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties (Counties in Idaho by population aged 18 to 64, 2025) [Data set]. Retrieved October 12, 2026, from https://www.census.gov/programs-surveys/popest/data/data-sets.html

MLA 9

Population Estimates Program, county population by age and sex: residents aged 18 to 64 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties, Counties in Idaho by population aged 18 to 64, 2025. U.S. Census Bureau, 25 June 2026, https://www.census.gov/programs-surveys/popest/data/data-sets.html. Invokely, https://invokely.ai/rankings/population-18-64/idaho-counties. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Census Bureau. 2026. Population Estimates Program, county population by age and sex: residents aged 18 to 64 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties. Counties in Idaho by population aged 18 to 64, 2025. Dataset. Accessed October 12, 2026. https://www.census.gov/programs-surveys/popest/data/data-sets.html. Also distributed by Invokely, https://invokely.ai/rankings/population-18-64/idaho-counties.

Harvard

U.S. Census Bureau (2026) Population Estimates Program, county population by age and sex: residents aged 18 to 64 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties, Counties in Idaho by population aged 18 to 64, 2025 [Dataset]. Available at: https://www.census.gov/programs-surveys/popest/data/data-sets.html, via Invokely: https://invokely.ai/rankings/population-18-64/idaho-counties (Accessed: 12 October 2026).

BibTeX
@misc{census_counties_in_idaho_by_2025,
  author = {{U.S. Census Bureau}},
  title = {{Population Estimates Program, county population by age and sex: residents aged 18 to 64 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties: Counties in Idaho by population aged 18 to 64, 2025}},
  year = {2026},
  howpublished = {Data set},
  url = {https://www.census.gov/programs-surveys/popest/data/data-sets.html},
  urldate = {2026-10-12},
  note = {Accessed via Invokely, https://invokely.ai/rankings/population-18-64/idaho-counties. Publisher attribution: U.S. Census Bureau. Population Estimates Program, county population by age and sex: residents aged 18 to 64 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties. https://www.census.gov/programs-surveys/popest/data/data-sets.html. Retrieved 2026-10-12.},
}
RIS
TY  - DATA
AU  - U.S. Census Bureau
TI  - Population Estimates Program, county population by age and sex: residents aged 18 to 64 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties: Counties in Idaho by population aged 18 to 64, 2025
PY  - 2026
DA  - 2026/06/25
PB  - U.S. Census Bureau
DB  - Invokely
UR  - https://www.census.gov/programs-surveys/popest/data/data-sets.html
L2  - https://invokely.ai/rankings/population-18-64/idaho-counties
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/population-18-64/idaho-counties.
N1  - Publisher attribution: U.S. Census Bureau. Population Estimates Program, county population by age and sex: residents aged 18 to 64 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties. https://www.census.gov/programs-surveys/popest/data/data-sets.html. Retrieved 2026-10-12.
ER  -
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Questions

Which county has the highest population aged 18 to 64?

Madison County, with 71.8% in 2025, according to the U.S. Census Bureau.

Which county has the lowest population aged 18 to 64?

Idaho County, with 48% in 2025.

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: residents aged 18 to 64 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties. Retrieved 2026-10-12.

Population aged 18 to 64: other rankings

Counties in Idaho: more rankings