Counties in Washington by median age on 1 July (US county estimates)

Jefferson County had the highest median age on 1 July (US county estimates) of 39 counties in 2018, at 59 years. Whitman County had the lowest, at 25.6 years. The median was 42 years. Source: the U.S. Census Bureau.

Highest59Jefferson County

Lowest25.6Whitman County

Median4239 counties

Map of counties, 2018

Under 36
36 to 38
38 to 42
42 to 46
46 to 51
51 and over

years, 2018. Source: U.S. Census Bureau, Population Estimates Program, county population by age and sex: median age (MEDIAN_AGE_TOT) on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2018

years. Source: U.S. Census Bureau, Population Estimates Program, county population by age and sex: median age (MEDIAN_AGE_TOT) on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage. Retrieved 2026-10-12.

Full ranking

Rank	Counties	2018 years	Change on 2017
1	Jefferson County	59	+0.5
2	San Juan County	55.8	-0.1
3	Pacific County	53.3	+0.3
4	Wahkiakum County	53.1	0
5	Clallam County	52.2	+0.5
6	Pend Oreille County	51.7	+0.4
7	Columbia County	51.4	+0.4
8	Ferry County	49.7	-0.4
9	Lincoln County	48.6	-0.2
10	Garfield County	47.9	-1.2
10	Stevens County	47.9	+0.2
12	Skamania County	46.2	-0.1
13	Mason County	46.1	-0.1
14	Klickitat County	45.9	-0.4
15	Island County	45.5	+0.3
16	Asotin County	44.8	0
17	Grays Harbor County	44.6	0
18	Okanogan County	44.5	+0.1
19	Lewis County	42.8	-0.1
20	Skagit County	42	+0.2
21	Cowlitz County	41	-0.3
22	Chelan County	40.9	+0.4
23	Kitsap County	39.5	+0.1
24	Thurston County	39.1	0
25	Walla Walla County	38.8	+0.4
26	Clark County	38.4	+0.2
27	Snohomish County	37.9	+0.1
28	Douglas County	37.8	-0.1
28	Spokane County	37.8	+0.2
30	Whatcom County	37.7	+0.3
31	King County	36.9	0
32	Pierce County	36.6	+0.2
33	Kittitas County	36.3	+0.7
34	Benton County	36.1	+0.2
35	Yakima County	33.8	+0.2
36	Grant County	33.7	+0.2
37	Franklin County	30.5	+0.3
38	Adams County	29.7	+0.2
39	Whitman County	25.6	+0.2

Other periods

About this ranking

Age that divides the resident population of a US county into two halves of equal size on 1 July, from Census Bureau population estimates calculated by single year of age.

Counties only: the county file has no state or national medians, and medians cannot be added up. A single-year estimate, unlike median_age, which for US places is a five-year American Community Survey estimate.

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: median age (MEDIAN_AGE_TOT) on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage. 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: median age (MEDIAN_AGE_TOT) on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage (Counties in Washington by median age on 1 July (US county estimates), 2018) [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: median age (MEDIAN_AGE_TOT) on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage, Counties in Washington by median age on 1 July (US county estimates), 2018. U.S. Census Bureau, 25 June 2026, https://www.census.gov/programs-surveys/popest/data/data-sets.html. Invokely, https://invokely.ai/rankings/median-age-july-1-us-counties/washington-counties?period=2018. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Census Bureau. 2026. Population Estimates Program, county population by age and sex: median age (MEDIAN_AGE_TOT) on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage. Counties in Washington by median age on 1 July (US county estimates), 2018. Dataset. Accessed October 12, 2026. https://www.census.gov/programs-surveys/popest/data/data-sets.html. Also distributed by Invokely, https://invokely.ai/rankings/median-age-july-1-us-counties/washington-counties?period=2018.

Harvard

U.S. Census Bureau (2026) Population Estimates Program, county population by age and sex: median age (MEDIAN_AGE_TOT) on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage, Counties in Washington by median age on 1 July (US county estimates), 2018 [Dataset]. Available at: https://www.census.gov/programs-surveys/popest/data/data-sets.html, via Invokely: https://invokely.ai/rankings/median-age-july-1-us-counties/washington-counties?period=2018 (Accessed: 12 October 2026).

BibTeX

@misc{census_counties_in_washington_by_2018,
  author = {{U.S. Census Bureau}},
  title = {{Population Estimates Program, county population by age and sex: median age (MEDIAN\_AGE\_TOT) on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage: Counties in Washington by median age on 1 July (US county estimates), 2018}},
  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/median-age-july-1-us-counties/washington-counties?period=2018. Publisher attribution: U.S. Census Bureau. Population Estimates Program, county population by age and sex: median age (MEDIAN\_AGE\_TOT) on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage. 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: median age (MEDIAN_AGE_TOT) on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage: Counties in Washington by median age on 1 July (US county estimates), 2018
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/median-age-july-1-us-counties/washington-counties?period=2018
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/median-age-july-1-us-counties/washington-counties?period=2018.
N1  - Publisher attribution: U.S. Census Bureau. Population Estimates Program, county population by age and sex: median age (MEDIAN_AGE_TOT) on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage. 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 median age on 1 July (US county estimates)?

Jefferson County, with 59 years in 2018, according to the U.S. Census Bureau.

Which county has the lowest median age on 1 July (US county estimates)?

Whitman County, with 25.6 years in 2018.

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: median age (MEDIAN_AGE_TOT) on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage. Retrieved 2026-10-12.