Counties in Washington by population under 18

Adams County had the highest population under 18 of 39 counties in 2023, at 33.2%. Jefferson County had the lowest, at 11.1%. The median was 20.1% and the figure for Washington was 21%. Source: the U.S. Census Bureau.

Highest33.2Adams County

Lowest11.1Jefferson County

Median20.139 counties

Washington21History

Map of counties, 2023

Under 17
17 to 19
19 to 20
20 to 22
22 and over

%, 2023. Source: Invokely calculation with data from U.S. Census Bureau. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2023

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

Full ranking

Rank	Counties	2023 (%)	Change on 2022
1	Adams County	33.2	-0.4 pts
2	Franklin County	30.1	-0.6 pts
3	Yakima County	27.6	-0.4 pts
4	Grant County	27.6	-0.4 pts
5	Benton County	25.4	-0.3 pts
6	Douglas County	23.3	-0.4 pts
7	Pierce County	22.5	-0.2 pts
8	Cowlitz County	22.2	-0.2 pts
9	Garfield County	22.1	-0.9 pts
10	Lewis County	22.1	-0 pts
11	Clark County	21.9	-0.4 pts
12	Snohomish County	21.9	-0.3 pts
13	Chelan County	21.8	-0 pts
14	Okanogan County	21.4	-0.3 pts
15	Spokane County	21.2	-0.2 pts
16	Stevens County	20.9	-0.1 pts
17	Lincoln County	20.8	-0.3 pts
18	Skagit County	20.8	-0.3 pts
19	Thurston County	20.6	-0.4 pts
20	Walla Walla County	20.1	-0.2 pts
21	Pend Oreille County	19.7	+0.1 pts
22	Grays Harbor County	19.5	-0.2 pts
23	Asotin County	19.5	-0.3 pts
24	Kitsap County	19.3	-0.3 pts
25	King County	19.2	-0.3 pts
26	Ferry County	19.1	+0.2 pts
27	Mason County	19	-0.1 pts
28	Whatcom County	18.4	-0.4 pts
29	Klickitat County	18.3	-0.4 pts
30	Skamania County	17.4	-0.3 pts
31	Kittitas County	17.3	-0.1 pts
32	Island County	16.8	-0.4 pts
33	Columbia County	16.7	+0.3 pts
34	Wahkiakum County	16.6	+0.3 pts
35	Whitman County	16.2	+0.2 pts
36	Clallam County	15.7	-0.2 pts
37	Pacific County	15.4	-0.6 pts
38	San Juan County	13.1	-0.5 pts
39	Jefferson County	11.1	-0.5 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 Washington by population under 18, 2023) [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 Washington by population under 18, 2023. 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/washington-counties?period=2023. 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 Washington by population under 18, 2023. 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/washington-counties?period=2023.

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 Washington by population under 18, 2023 [Dataset]. Available at: https://www.census.gov/programs-surveys/popest/data/data-sets.html, via Invokely: https://invokely.ai/rankings/population-under-18/washington-counties?period=2023 (Accessed: 12 October 2026).

BibTeX

@misc{census_counties_in_washington_by_2023,
  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 Washington by population under 18, 2023}},
  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/washington-counties?period=2023. 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 Washington by population under 18, 2023
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/washington-counties?period=2023
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/population-under-18/washington-counties?period=2023.
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?

Adams County, with 33.2% in 2023, according to the U.S. Census Bureau.

Which county has the lowest population under 18?

Jefferson County, with 11.1% in 2023.

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.