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

Counties in Idaho by population aged 18 to 64

Madison County had the highest population aged 18 to 64 of 44 counties in 2024, at 71.9%. Idaho County had the lowest, at 48.6%. The median was 54.3% and the figure for Idaho was 58%. Source: the U.S. Census Bureau.

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Highest71.9Madison County
Lowest48.6Idaho County
Median54.344 counties
Idaho58History

Map of counties, 2024

Ada County: 61 %Adams County: 52 %Bannock County: 58.7 %Bear Lake County: 50.9 %Benewah County: 51.5 %Bingham County: 55.5 %Blaine County: 56.5 %Boise County: 53.6 %Bonner County: 52.7 %Bonneville County: 56.6 %Boundary County: 50.8 %Butte County: 51.2 %Camas County: 51.7 %Canyon County: 58.3 %Caribou County: 52.7 %Cassia County: 54.2 %Clark County: 53.5 %Clearwater County: 53.8 %Custer County: 50.4 %Elmore County: 60.4 %Franklin County: 54.4 %Fremont County: 56 %Gem County: 53.4 %Gooding County: 56.1 %Idaho County: 48.6 %Jefferson County: 55.5 %Jerome County: 56.3 %Kootenai County: 55.9 %Latah County: 63.9 %Lemhi County: 49.6 %Lewis County: 51.1 %Lincoln County: 56.7 %Madison County: 71.9 %Minidoka County: 55.2 %Nez Perce County: 56.8 %Oneida County: 51.3 %Owyhee County: 56.4 %Payette County: 53.9 %Power County: 55.4 %Shoshone County: 54.1 %Teton County: 63.2 %Twin Falls County: 56.7 %Valley County: 53.1 %Washington County: 52.4 %
  • Under 51
  • 51 to 53
  • 53 to 54
  • 54 to 56
  • 56 to 57
  • 57 and over
%, 2024. Source: Invokely calculation with data from U.S. Census Bureau. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2024

Madison County: 71.9 %Madison County71.9Latah County: 63.9 %Latah County63.9Teton County: 63.2 %Teton County63.2Ada County: 61 %Ada County61Elmore County: 60.4 %Elmore County60.4Bannock County: 58.7 %Bannock County58.7Canyon County: 58.3 %Canyon County58.3Nez Perce County: 56.8 %Nez Perce County56.8Lincoln County: 56.7 %Lincoln County56.7Twin Falls County: 56.7 %Twin Falls County56.7Bonneville County: 56.6 %Bonneville County56.6Blaine County: 56.5 %Blaine County56.5Owyhee County: 56.4 %Owyhee County56.4Jerome County: 56.3 %Jerome County56.3Gooding County: 56.1 %Gooding County56.1Fremont County: 56 %Fremont County56Kootenai County: 55.9 %Kootenai County55.9Jefferson County: 55.5 %Jefferson County55.5Bingham County: 55.5 %Bingham County55.5Power County: 55.4 %Power County55.4Minidoka County: 55.2 %Minidoka County55.2Franklin County: 54.4 %Franklin County54.4Cassia County: 54.2 %Cassia County54.2Shoshone County: 54.1 %Shoshone County54.1Payette County: 53.9 %Payette County53.9Clearwater County: 53.8 %Clearwater County53.8Boise County: 53.6 %Boise County53.6Clark County: 53.5 %Clark County53.5Gem County: 53.4 %Gem County53.4Valley County: 53.1 %Valley County53.1Caribou County: 52.7 %Caribou County52.7Bonner County: 52.7 %Bonner County52.7Washington County: 52.4 %Washington County52.4Adams County: 52 %Adams County52Camas County: 51.7 %Camas County51.7Benewah County: 51.5 %Benewah County51.5Oneida County: 51.3 %Oneida County51.3Butte County: 51.2 %Butte County51.2Lewis County: 51.1 %Lewis County51.1Bear Lake County: 50.9 %Bear Lake County50.9Boundary County: 50.8 %Boundary County50.8Custer County: 50.4 %Custer County50.4Lemhi County: 49.6 %Lemhi County49.6Idaho County: 48.6 %Idaho County48.6Madison County: 71.9 %Madison County71.9Latah County: 63.9 %Latah County63.9Teton County: 63.2 %Teton County63.2Ada County: 61 %Ada County61Elmore County: 60.4 %Elmore County60.4Bannock County: 58.7 %Bannock County58.7Canyon County: 58.3 %Canyon County58.3Nez Perce County: 56.8 %Nez Perce County56.8Lincoln County: 56.7 %Lincoln County56.7Twin Falls County: 56.7 %Twin Falls County56.7Bonneville County: 56.6 %Bonneville County56.6Blaine County: 56.5 %Blaine County56.5Owyhee County: 56.4 %Owyhee County56.4Jerome County: 56.3 %Jerome County56.3Gooding County: 56.1 %Gooding County56.1Fremont County: 56 %Fremont County56Kootenai County: 55.9 %Kootenai County55.9Jefferson County: 55.5 %Jefferson County55.5Bingham County: 55.5 %Bingham County55.5Power County: 55.4 %Power County55.4Minidoka County: 55.2 %Minidoka County55.2Franklin County: 54.4 %Franklin County54.4Cassia County: 54.2 %Cassia County54.2Shoshone County: 54.1 %Shoshone County54.1Payette County: 53.9 %Payette County53.9Clearwater County: 53.8 %Clearwater County53.8Boise County: 53.6 %Boise County53.6Clark County: 53.5 %Clark County53.5Gem County: 53.4 %Gem County53.4Valley County: 53.1 %Valley County53.1Caribou County: 52.7 %Caribou County52.7Bonner County: 52.7 %Bonner County52.7Washington County: 52.4 %Washington County52.4Adams County: 52 %Adams County52Camas County: 51.7 %Camas County51.7Benewah County: 51.5 %Benewah County51.5Oneida County: 51.3 %Oneida County51.3Butte County: 51.2 %Butte County51.2Lewis County: 51.1 %Lewis County51.1Bear Lake County: 50.9 %Bear Lake County50.9Boundary County: 50.8 %Boundary County50.8Custer County: 50.4 %Custer County50.4Lemhi County: 49.6 %Lemhi County49.6Idaho County: 48.6 %Idaho County48.6
%. Source: Invokely calculation with data from U.S. Census Bureau. Retrieved 2026-10-12.

Full ranking

RankCounties2024 (%)Change on 2023
1Madison County71.9-0.2 pts
2Latah County63.9-0.3 pts
3Teton County63.2+0.5 pts
4Ada County61-0 pts
5Elmore County60.4-0.2 pts
6Bannock County58.7+0.1 pts
7Canyon County58.3+0.2 pts
8Nez Perce County56.8-0 pts
9Lincoln County56.7+0.1 pts
10Twin Falls County56.7+0.1 pts
11Bonneville County56.6+0.2 pts
12Blaine County56.50 pts
13Owyhee County56.4+0.5 pts
14Jerome County56.3+0.2 pts
15Gooding County56.1+0.6 pts
16Fremont County56+0.5 pts
17Kootenai County55.9-0.3 pts
18Jefferson County55.5+0.3 pts
19Bingham County55.5+0.3 pts
20Power County55.4+0.8 pts
21Minidoka County55.2+0.1 pts
22Franklin County54.4+0.2 pts
23Cassia County54.2+0.4 pts
24Shoshone County54.1-0.1 pts
25Payette County53.9-0.2 pts
26Clearwater County53.8-0.2 pts
27Boise County53.6-0.8 pts
28Clark County53.5+0.4 pts
29Gem County53.4-0.2 pts
30Valley County53.1-0.4 pts
31Caribou County52.7+0.1 pts
32Bonner County52.7-0.4 pts
33Washington County52.4+0.4 pts
34Adams County52+0.8 pts
35Camas County51.7-0.1 pts
36Benewah County51.5-0 pts
37Oneida County51.3-0.2 pts
38Butte County51.2-0.4 pts
39Lewis County51.1-0.1 pts
40Bear Lake County50.9-0.3 pts
41Boundary County50.8+0.1 pts
42Custer County50.4-1.3 pts
43Lemhi County49.6-0.4 pts
44Idaho County48.6-0.6 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, 2024) [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, 2024. 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?period=2024. 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, 2024. 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?period=2024.

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, 2024 [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?period=2024 (Accessed: 12 October 2026).

BibTeX
@misc{census_counties_in_idaho_by_2024,
  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, 2024}},
  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?period=2024. 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, 2024
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?period=2024
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/population-18-64/idaho-counties?period=2024.
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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Rank Counties in Idaho by population aged 18 to 64 using official data, and cite the source.
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Questions

Which county has the highest population aged 18 to 64?

Madison County, with 71.9% in 2024, according to the U.S. Census Bureau.

Which county has the lowest population aged 18 to 64?

Idaho County, with 48.6% in 2024.

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