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 2019, at 73.2%. Lemhi County had the lowest, at 51%. The median was 55% and the figure for Idaho was 58.2%. Source: the U.S. Census Bureau.

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Highest73.2Madison County
Lowest51Lemhi County
Median5544 counties
Idaho58.2History

Map of counties, 2019

Ada County: 61.1 %Adams County: 53.4 %Bannock County: 58.8 %Bear Lake County: 51.1 %Benewah County: 52.8 %Bingham County: 54.5 %Blaine County: 57.2 %Boise County: 57.1 %Bonner County: 54.7 %Bonneville County: 56 %Boundary County: 51.3 %Butte County: 52.1 %Camas County: 55.6 %Canyon County: 57.2 %Caribou County: 52.6 %Cassia County: 53.7 %Clark County: 57.5 %Clearwater County: 55.5 %Custer County: 54.5 %Elmore County: 60.9 %Franklin County: 52.9 %Fremont County: 54.7 %Gem County: 53.7 %Gooding County: 54.8 %Idaho County: 51.7 %Jefferson County: 54.1 %Jerome County: 55.8 %Kootenai County: 56.9 %Latah County: 66.1 %Lemhi County: 51 %Lewis County: 54.3 %Lincoln County: 56.3 %Madison County: 73.2 %Minidoka County: 55.4 %Nez Perce County: 57.9 %Oneida County: 51 %Owyhee County: 55.2 %Payette County: 54.3 %Power County: 53.8 %Shoshone County: 56.1 %Teton County: 61.1 %Twin Falls County: 56.3 %Valley County: 55.5 %Washington County: 51.1 %
  • Under 53
  • 53 to 54
  • 54 to 55
  • 55 to 56
  • 56 to 57
  • 57 and over
%, 2019. Source: Invokely calculation with data from U.S. Census Bureau. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2019

Madison County: 73.2 %Madison County73.2Latah County: 66.1 %Latah County66.1Teton County: 61.1 %Teton County61.1Ada County: 61.1 %Ada County61.1Elmore County: 60.9 %Elmore County60.9Bannock County: 58.8 %Bannock County58.8Nez Perce County: 57.9 %Nez Perce County57.9Clark County: 57.5 %Clark County57.5Blaine County: 57.2 %Blaine County57.2Canyon County: 57.2 %Canyon County57.2Boise County: 57.1 %Boise County57.1Kootenai County: 56.9 %Kootenai County56.9Twin Falls County: 56.3 %Twin Falls County56.3Lincoln County: 56.3 %Lincoln County56.3Shoshone County: 56.1 %Shoshone County56.1Bonneville County: 56 %Bonneville County56Jerome County: 55.8 %Jerome County55.8Camas County: 55.6 %Camas County55.6Valley County: 55.5 %Valley County55.5Clearwater County: 55.5 %Clearwater County55.5Minidoka County: 55.4 %Minidoka County55.4Owyhee County: 55.2 %Owyhee County55.2Gooding County: 54.8 %Gooding County54.8Fremont County: 54.7 %Fremont County54.7Bonner County: 54.7 %Bonner County54.7Custer County: 54.5 %Custer County54.5Bingham County: 54.5 %Bingham County54.5Lewis County: 54.3 %Lewis County54.3Payette County: 54.3 %Payette County54.3Jefferson County: 54.1 %Jefferson County54.1Power County: 53.8 %Power County53.8Gem County: 53.7 %Gem County53.7Cassia County: 53.7 %Cassia County53.7Adams County: 53.4 %Adams County53.4Franklin County: 52.9 %Franklin County52.9Benewah County: 52.8 %Benewah County52.8Caribou County: 52.6 %Caribou County52.6Butte County: 52.1 %Butte County52.1Idaho County: 51.7 %Idaho County51.7Boundary County: 51.3 %Boundary County51.3Washington County: 51.1 %Washington County51.1Bear Lake County: 51.1 %Bear Lake County51.1Oneida County: 51 %Oneida County51Lemhi County: 51 %Lemhi County51Madison County: 73.2 %Madison County73.2Latah County: 66.1 %Latah County66.1Teton County: 61.1 %Teton County61.1Ada County: 61.1 %Ada County61.1Elmore County: 60.9 %Elmore County60.9Bannock County: 58.8 %Bannock County58.8Nez Perce County: 57.9 %Nez Perce County57.9Clark County: 57.5 %Clark County57.5Blaine County: 57.2 %Blaine County57.2Canyon County: 57.2 %Canyon County57.2Boise County: 57.1 %Boise County57.1Kootenai County: 56.9 %Kootenai County56.9Twin Falls County: 56.3 %Twin Falls County56.3Lincoln County: 56.3 %Lincoln County56.3Shoshone County: 56.1 %Shoshone County56.1Bonneville County: 56 %Bonneville County56Jerome County: 55.8 %Jerome County55.8Camas County: 55.6 %Camas County55.6Valley County: 55.5 %Valley County55.5Clearwater County: 55.5 %Clearwater County55.5Minidoka County: 55.4 %Minidoka County55.4Owyhee County: 55.2 %Owyhee County55.2Gooding County: 54.8 %Gooding County54.8Fremont County: 54.7 %Fremont County54.7Bonner County: 54.7 %Bonner County54.7Custer County: 54.5 %Custer County54.5Bingham County: 54.5 %Bingham County54.5Lewis County: 54.3 %Lewis County54.3Payette County: 54.3 %Payette County54.3Jefferson County: 54.1 %Jefferson County54.1Power County: 53.8 %Power County53.8Gem County: 53.7 %Gem County53.7Cassia County: 53.7 %Cassia County53.7Adams County: 53.4 %Adams County53.4Franklin County: 52.9 %Franklin County52.9Benewah County: 52.8 %Benewah County52.8Caribou County: 52.6 %Caribou County52.6Butte County: 52.1 %Butte County52.1Idaho County: 51.7 %Idaho County51.7Boundary County: 51.3 %Boundary County51.3Washington County: 51.1 %Washington County51.1Bear Lake County: 51.1 %Bear Lake County51.1Oneida County: 51 %Oneida County51Lemhi County: 51 %Lemhi County51
%. Source: Invokely calculation with data from U.S. Census Bureau. Retrieved 2026-10-12.

Full ranking

RankCounties2019 (%)Change on 2018
1Madison County73.2+0.4 pts
2Latah County66.1-0.4 pts
3Teton County61.10 pts
4Ada County61.1-0.2 pts
5Elmore County60.9-0.5 pts
6Bannock County58.8-0.3 pts
7Nez Perce County57.9-0.5 pts
8Clark County57.5-0.1 pts
9Blaine County57.2-0.1 pts
10Canyon County57.2+0.2 pts
11Boise County57.1-1 pts
12Kootenai County56.9-0.4 pts
13Twin Falls County56.3-0.2 pts
14Lincoln County56.3+0.4 pts
15Shoshone County56.1-0.2 pts
16Bonneville County56+0.1 pts
17Jerome County55.8-0.3 pts
18Camas County55.6+0.1 pts
19Valley County55.5-0.9 pts
20Clearwater County55.5-0.2 pts
21Minidoka County55.4-0.1 pts
22Owyhee County55.2+0.3 pts
23Gooding County54.8+0.1 pts
24Fremont County54.7+0.1 pts
25Bonner County54.7-0.8 pts
26Custer County54.5-0.8 pts
27Bingham County54.5-0.1 pts
28Lewis County54.3+0.7 pts
29Payette County54.3-0.2 pts
30Jefferson County54.1+0.2 pts
31Power County53.8+0.2 pts
32Gem County53.7-0.2 pts
33Cassia County53.70 pts
34Adams County53.4-0.6 pts
35Franklin County52.9-0.1 pts
36Benewah County52.8-0.2 pts
37Caribou County52.6+0.1 pts
38Butte County52.1-0.6 pts
39Idaho County51.7-0.6 pts
40Boundary County51.3-0.9 pts
41Washington County51.1-0.4 pts
42Bear Lake County51.1-0.2 pts
43Oneida County51-0.2 pts
44Lemhi County51-0.5 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, 2019) [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, 2019. 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=2019. 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, 2019. 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=2019.

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, 2019 [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=2019 (Accessed: 12 October 2026).

BibTeX
@misc{census_counties_in_idaho_by_2019,
  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, 2019}},
  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=2019. 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, 2019
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=2019
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/population-18-64/idaho-counties?period=2019.
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 73.2% in 2019, according to the U.S. Census Bureau.

Which county has the lowest population aged 18 to 64?

Lemhi County, with 51% in 2019.

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