Counties in Washington by population under 18

Adams County had the highest population under 18 of 39 counties in 2016, at 34.3%. Jefferson County had the lowest, at 13%. The median was 20.9% and the figure for Washington was 22.5%. Source: the U.S. Census Bureau.

Highest34.3Adams County

Lowest13Jefferson County

Median20.939 counties

Washington22.5History

All counties, 2016

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

Full ranking

Rank	Counties	2016 (%)	Change on 2015
1	Adams County	34.3	-0 pts
2	Franklin County	32.9	-0.3 pts
3	Grant County	29.5	-0.3 pts
4	Yakima County	29.3	-0.1 pts
5	Benton County	26.8	-0 pts
6	Douglas County	26	-0.1 pts
7	Clark County	24.7	-0.3 pts
8	Pierce County	23.5	-0.1 pts
9	Chelan County	23.5	-0.3 pts
10	Snohomish County	23.2	-0.1 pts
11	Cowlitz County	22.9	0 pts
12	Okanogan County	22.4	-0.1 pts
13	Spokane County	22.4	-0.1 pts
14	Skagit County	22.2	-0.3 pts
15	Lewis County	22.2	0 pts
16	Thurston County	22	-0.2 pts
17	Stevens County	21.9	-0.1 pts
18	Walla Walla County	21.4	0 pts
19	Lincoln County	21	-0.4 pts
20	Garfield County	20.9	+0.7 pts
21	Kitsap County	20.8	-0.1 pts
22	King County	20.8	-0.1 pts
23	Asotin County	20.8	+0.1 pts
24	Grays Harbor County	20.5	-0.1 pts
25	Whatcom County	20.3	-0.1 pts
26	Skamania County	20	-0.1 pts
27	Klickitat County	19.8	-0.4 pts
28	Pend Oreille County	19.1	-0.4 pts
29	Ferry County	19	-0.4 pts
30	Mason County	19	-0.1 pts
31	Kittitas County	18.7	-0.2 pts
32	Island County	18.5	-0.1 pts
33	Columbia County	18.2	-0.1 pts
34	Wahkiakum County	18.1	+0.7 pts
35	Pacific County	17.6	-0.1 pts
36	Clallam County	17.2	-0.2 pts
37	Whitman County	15.7	+0.2 pts
38	San Juan County	14.5	-0.2 pts
39	Jefferson County	13	-0.4 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, 2016) [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, 2016. 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=2016. 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, 2016. 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=2016.

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, 2016 [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=2016 (Accessed: 12 October 2026).

BibTeX

@misc{census_counties_in_washington_by_2016,
  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, 2016}},
  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=2016. 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, 2016
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=2016
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/population-under-18/washington-counties?period=2016.
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 34.3% in 2016, according to the U.S. Census Bureau.

Which county has the lowest population under 18?

Jefferson County, with 13% in 2016.

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.