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 2015, at 57.2 years. Whitman County had the lowest, at 24.8 years. The median was 41.6 years. Source: the U.S. Census Bureau.

Highest57.2Jefferson County

Lowest24.8Whitman County

Median41.639 counties

Map of counties, 2015

Under 36
36 to 38
38 to 42
42 to 46
46 to 50
50 and over

years, 2015. 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, 2015

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	2015 years	Change on 2014
1	Jefferson County	57.2	+0.8
2	San Juan County	55.1	+0.4
3	Wahkiakum County	53.5	+0.7
4	Pacific County	52.5	+0.2
5	Clallam County	51.1	+0.4
5	Columbia County	51.1	+0.7
7	Pend Oreille County	50.7	+0.3
8	Garfield County	49.8	-0.3
9	Ferry County	49.2	+0.6
10	Lincoln County	49.1	0
11	Stevens County	47.1	+0.1
12	Klickitat County	46.4	+0.4
13	Mason County	46.2	+0.4
14	Skamania County	46	+0.6
15	Island County	45.3	+0.1
16	Asotin County	44.9	+0.5
17	Okanogan County	44.3	+0.4
18	Grays Harbor County	43.9	+0.4
19	Lewis County	43.1	0
20	Cowlitz County	41.6	-0.1
20	Skagit County	41.6	+0.2
22	Chelan County	40.1	+0.1
23	Kitsap County	39.4	-0.5
24	Thurston County	39	+0.4
25	Walla Walla County	38	+0.2
26	Clark County	37.9	+0.1
26	Douglas County	37.9	0
26	Snohomish County	37.9	+0.1
29	Spokane County	37.5	0
30	Whatcom County	37.1	+0.1
31	King County	37	-0.1
32	Pierce County	36.3	+0.3
33	Benton County	35.8	0
34	Kittitas County	34.8	+1
35	Yakima County	33.3	+0.2
36	Grant County	33	+0.2
37	Franklin County	29.8	+0.3
38	Adams County	29.5	0
39	Whitman County	24.8	+0.1

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), 2015) [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), 2015. 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=2015. 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), 2015. 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=2015.

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), 2015 [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=2015 (Accessed: 12 October 2026).

BibTeX

@misc{census_counties_in_washington_by_2015,
  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), 2015}},
  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=2015. 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), 2015
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=2015
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/median-age-july-1-us-counties/washington-counties?period=2015.
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 57.2 years in 2015, according to the U.S. Census Bureau.

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

Whitman County, with 24.8 years in 2015.

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.