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

Adams County had the highest median age on 1 July (US county estimates) of 44 counties in 2023, at 53.3 years. Madison County had the lowest, at 22.5 years. The median was 39.6 years. Source: the U.S. Census Bureau.

Highest53.3Adams County

Lowest22.5Madison County

Median39.644 counties

Map of counties, 2023

Under 34
34 to 37
37 to 40
40 to 45
45 to 49
49 and over

years, 2023. 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, 2023

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	2023 years	Change on 2022
1	Adams County	53.3	-0.3
2	Boise County	53	+0.4
3	Custer County	52.3	+0.1
4	Lemhi County	52.2	-0.1
5	Clearwater County	51.9	-0.2
6	Idaho County	50.5	-0.3
7	Valley County	49.7	-0.3
8	Camas County	49.2	-0.4
9	Bonner County	48.4	-0.1
10	Lewis County	47.2	-0.2
11	Blaine County	46.4	+0.2
12	Benewah County	45.9	-0.4
12	Shoshone County	45.9	-0.4
14	Boundary County	45.3	+0.3
15	Washington County	45	-0.4
16	Butte County	44.4	-0.3
17	Gem County	44.3	0
18	Nez Perce County	41.9	+0.3
19	Kootenai County	41.6	+0.3
20	Bear Lake County	40.7	+0.6
21	Teton County	40.1	+0.7
22	Payette County	39.7	+0.1
23	Oneida County	39.5	-0.8
24	Clark County	38.7	+1.6
25	Ada County	38.6	+0.3
26	Owyhee County	38.5	+0.3
27	Gooding County	37.8	0
28	Caribou County	37.6	+0.1
28	Fremont County	37.6	-0.2
30	Twin Falls County	36.7	+0.2
31	Lincoln County	36	-0.2
32	Minidoka County	35.4	0
33	Bingham County	35.3	+0.2
34	Bannock County	35.1	+0.2
35	Canyon County	35	+0.2
36	Power County	34.9	-0.6
37	Franklin County	34.3	+0.3
38	Jerome County	34.1	+0.2
39	Bonneville County	33.9	+0.3
40	Elmore County	33.7	+0.2
41	Cassia County	33	-0.2
41	Jefferson County	33	+0.4
43	Latah County	31.1	+0.1
44	Madison County	22.5	0

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 Idaho by median age on 1 July (US county estimates), 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: 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 Idaho by median age on 1 July (US county estimates), 2023. 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/idaho-counties?period=2023. 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 Idaho by median age on 1 July (US county estimates), 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/median-age-july-1-us-counties/idaho-counties?period=2023.

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 Idaho by median age on 1 July (US county estimates), 2023 [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/idaho-counties?period=2023 (Accessed: 12 October 2026).

BibTeX

@misc{census_counties_in_idaho_by_2023,
  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 Idaho by median age on 1 July (US county estimates), 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/median-age-july-1-us-counties/idaho-counties?period=2023. 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 Idaho by median age on 1 July (US county estimates), 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/median-age-july-1-us-counties/idaho-counties?period=2023
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/median-age-july-1-us-counties/idaho-counties?period=2023.
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)?

Adams County, with 53.3 years in 2023, according to the U.S. Census Bureau.

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

Madison County, with 22.5 years 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: 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.