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 2020, at 59.8 years. Whitman County had the lowest, at 25.3 years. The median was 42.2 years. Source: the U.S. Census Bureau.

Highest59.8Jefferson County

Lowest25.3Whitman County

Median42.239 counties

All counties, 2020

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	2020 years	Change on 2019
1	Jefferson County	59.8	+0.5
2	San Juan County	56.5	+0.7
3	Wahkiakum County	54.3	+0.5
4	Pacific County	54	+0.3
5	Clallam County	52.9	+0.4
6	Columbia County	52.6	0
7	Ferry County	51.4	+0.1
8	Pend Oreille County	51.2	-0.6
9	Lincoln County	48.3	-0.3
10	Garfield County	48.1	+0.3
11	Stevens County	48	-0.1
12	Skamania County	47.3	+1
13	Klickitat County	46.2	+0.4
14	Island County	45.7	0
15	Mason County	45.5	-0.5
16	Asotin County	45.4	+0.3
17	Grays Harbor County	44.6	-0.1
17	Okanogan County	44.6	+0.1
19	Lewis County	42.5	-0.3
20	Skagit County	42.2	-0.1
21	Chelan County	41	0
21	Cowlitz County	41	0
23	Kitsap County	39.8	+0.2
24	Thurston County	39.5	+0.1
25	Walla Walla County	39.3	+0.2
26	Clark County	38.8	+0.2
27	Douglas County	38.4	+0.4
28	Snohomish County	38.2	+0.1
28	Whatcom County	38.2	+0.3
30	Spokane County	38	+0.1
31	King County	36.9	0
31	Pierce County	36.9	+0.1
33	Benton County	36.4	+0.2
34	Kittitas County	34.6	-2.5
35	Grant County	34.1	+0.1
36	Yakima County	34	0
37	Franklin County	30.8	0
38	Adams County	29.7	+0.1
39	Whitman County	25.3	-0.3

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), 2020) [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), 2020. 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=2020. 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), 2020. 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=2020.

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), 2020 [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=2020 (Accessed: 12 October 2026).

BibTeX

@misc{census_counties_in_washington_by_2020,
  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), 2020}},
  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=2020. 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), 2020
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=2020
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/median-age-july-1-us-counties/washington-counties?period=2020.
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 59.8 years in 2020, according to the U.S. Census Bureau.

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

Whitman County, with 25.3 years in 2020.

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.