Counties in Idaho by population under 18

Jefferson County had the highest population under 18 of 44 counties in 2022, at 32.9%. Clearwater County had the lowest, at 16.4%. The median was 24.1% and the figure for Idaho was 24.4%. Source: the U.S. Census Bureau.

Highest32.9Jefferson County

Lowest16.4Clearwater County

Median24.144 counties

Idaho24.4History

All counties, 2022

%. Source: Invokely calculation with data from U.S. Census Bureau. Retrieved 2026-10-12.

Full ranking

Rank	Counties	2022 (%)	Change on 2021
1	Jefferson County	32.9	-0.5 pts
2	Franklin County	30.9	-0.4 pts
3	Cassia County	30.8	-0 pts
4	Jerome County	29.8	0 pts
5	Bonneville County	29.6	-0.5 pts
6	Power County	29.6	-0.2 pts
7	Bingham County	29.5	-0.5 pts
8	Caribou County	28.6	-0.4 pts
9	Clark County	28.4	+0.8 pts
10	Minidoka County	28.2	-0.2 pts
11	Bear Lake County	27.7	+0.1 pts
12	Oneida County	27.3	+0.6 pts
13	Lincoln County	27.2	0 pts
14	Canyon County	27	-0.4 pts
15	Gooding County	26.6	-0.6 pts
16	Twin Falls County	26.5	-0.4 pts
17	Owyhee County	26.3	-0.2 pts
18	Fremont County	26.1	-0.2 pts
19	Payette County	25.6	-0.4 pts
20	Bannock County	25.6	-0.2 pts
21	Butte County	24.2	-0.2 pts
22	Elmore County	24.2	-0.3 pts
23	Boundary County	24	+0.6 pts
24	Teton County	23.5	-0.9 pts
25	Gem County	22.8	-0.2 pts
26	Washington County	22.6	-0.5 pts
27	Kootenai County	22.4	-0.2 pts
28	Benewah County	22.4	+0.5 pts
29	Ada County	22.4	-0.5 pts
30	Lewis County	21.9	+0.1 pts
31	Madison County	21.2	+0.4 pts
32	Nez Perce County	21.1	+0.1 pts
33	Shoshone County	20.4	+0.3 pts
34	Latah County	19.9	+0.3 pts
35	Bonner County	19.6	+0.1 pts
36	Idaho County	19.6	+0.1 pts
37	Camas County	19.5	+0.4 pts
38	Blaine County	19.4	-0.6 pts
39	Lemhi County	18.2	+0.1 pts
40	Valley County	18.2	+0.1 pts
41	Custer County	17.4	+0.3 pts
42	Adams County	17.4	+0.2 pts
43	Boise County	17	+0.1 pts
44	Clearwater County	16.4	+0.1 pts

Other periods

About this ranking

Residents aged 0 to 17 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.

Uses the US age of majority. Not comparable with population_0_14_share, which stops at 14.

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 0 to 17 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 0 to 17 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 under 18, 2022) [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 0 to 17 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 under 18, 2022. U.S. Census Bureau, 25 June 2026, https://www.census.gov/programs-surveys/popest/data/data-sets.html. Invokely, https://invokely.ai/rankings/population-under-18/idaho-counties?period=2022. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Census Bureau. 2026. Population Estimates Program, county population by age and sex: residents aged 0 to 17 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 under 18, 2022. 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-under-18/idaho-counties?period=2022.

Harvard

U.S. Census Bureau (2026) Population Estimates Program, county population by age and sex: residents aged 0 to 17 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 under 18, 2022 [Dataset]. Available at: https://www.census.gov/programs-surveys/popest/data/data-sets.html, via Invokely: https://invokely.ai/rankings/population-under-18/idaho-counties?period=2022 (Accessed: 12 October 2026).

BibTeX

@misc{census_counties_in_idaho_by_2022,
  author = {{U.S. Census Bureau}},
  title = {{Population Estimates Program, county population by age and sex: residents aged 0 to 17 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 under 18, 2022}},
  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-under-18/idaho-counties?period=2022. Publisher attribution: U.S. Census Bureau. Population Estimates Program, county population by age and sex: residents aged 0 to 17 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 0 to 17 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 under 18, 2022
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-under-18/idaho-counties?period=2022
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/population-under-18/idaho-counties?period=2022.
N1  - Publisher attribution: U.S. Census Bureau. Population Estimates Program, county population by age and sex: residents aged 0 to 17 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 under 18?

Jefferson County, with 32.9% in 2022, according to the U.S. Census Bureau.

Which county has the lowest population under 18?

Clearwater County, with 16.4% in 2022.

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 0 to 17 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.