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 2017, at 54.1 years. Madison County had the lowest, at 23.1 years. The median was 38.5 years. Source: the U.S. Census Bureau.

Highest54.1Adams County

Lowest23.1Madison County

Median38.544 counties

Map of counties, 2017

Under 34
34 to 36
36 to 39
39 to 44
44 to 48
48 and over

years, 2017. 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, 2017

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	2017 years	Change on 2016
1	Adams County	54.1	-0.5
2	Custer County	52.9	-0.4
3	Boise County	52.8	+0.1
4	Lemhi County	52.6	-0.1
5	Idaho County	50.9	+0.1
6	Clearwater County	50.7	+0.1
7	Valley County	49	-0.1
8	Bonner County	48.5	0
9	Lewis County	48.3	+0.7
10	Shoshone County	48.2	+0.2
11	Benewah County	46.9	-0.3
12	Camas County	46.6	+1.2
13	Washington County	45.5	+0.6
14	Boundary County	45.3	+0.2
15	Gem County	44.1	-0.1
16	Blaine County	43.7	+0.5
17	Butte County	43.3	-0.7
18	Kootenai County	40.6	+0.1
19	Nez Perce County	40.4	-0.3
20	Oneida County	40.1	+0.5
21	Bear Lake County	39.5	0
22	Payette County	38.8	+0.1
23	Owyhee County	38.2	-0.4
24	Caribou County	37.2	-0.2
25	Clark County	37.1	+0.6
26	Gooding County	36.6	+0.1
27	Ada County	36.5	+0.3
27	Teton County	36.5	+0.5
29	Fremont County	36.4	-0.3
30	Minidoka County	35.4	0
31	Power County	34.8	+0.4
32	Lincoln County	34.7	+0.2
32	Twin Falls County	34.7	0
34	Bingham County	34	+0.2
35	Bannock County	33.7	+0.3
36	Canyon County	33.6	+0.3
36	Franklin County	33.6	+0.6
38	Cassia County	32.9	+0.3
39	Bonneville County	32.8	+0.1
40	Jerome County	32.7	+0.2
41	Elmore County	32.1	+0.1
42	Jefferson County	31.6	+0.1
43	Latah County	29.5	+0.1
44	Madison County	23.1	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), 2017) [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), 2017. 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=2017. 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), 2017. 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=2017.

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), 2017 [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=2017 (Accessed: 12 October 2026).

BibTeX

@misc{census_counties_in_idaho_by_2017,
  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), 2017}},
  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=2017. 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), 2017
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=2017
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/median-age-july-1-us-counties/idaho-counties?period=2017.
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  -

Embed this chart

Paste this code into a web page or a blog post. The chart shows the latest figures as they are published, with the source and a link back to this page.

Embed code

<iframe src="https://invokely.ai/embed/rankings/median-age-july-1-us-counties/idaho-counties?period=2017" width="760" height="500" title="Counties in Idaho by median age on 1 July (US county estimates), 2017, chart from Invokely" loading="lazy" style="border:0;width:100%;max-width:760px" referrerpolicy="strict-origin-when-cross-origin"></iframe>

Sites that read oEmbed links, such as WordPress, can show the chart when you paste the link to this page.

Use this data in your AI agent

Invokely serves this figure to AI assistants through MCP and to code through a REST API, with the source and citation attached. Ask your assistant:

Rank Counties in Idaho by median age on 1 July (US county estimates) using official data, and cite the source.

rank_places {"indicator":"median_age_pep","level":"province","within":"Idaho","limit":10}
GET https://invokely.ai/api/v1/rank?indicator=median_age_pep&level=province&within=Idaho&limit=10

Connect Claude, ChatGPT or Cursor in one step. The trial answers 25 calls a day without an account.

Questions

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

Adams County, with 54.1 years in 2017, according to the U.S. Census Bureau.

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

Madison County, with 23.1 years in 2017.

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.