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 2021, at 54.2 years. Madison County had the lowest, at 22.6 years. The median was 39.3 years. Source: the U.S. Census Bureau.
Map of counties, 2021
- Under 34
- 34 to 37
- 37 to 39
- 39 to 45
- 45 to 50
- 50 and over
All counties, 2021
Full ranking
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
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), 2021) [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), 2021. 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=2021. 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), 2021. 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=2021.
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), 2021 [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=2021 (Accessed: 12 October 2026).
BibTeX
@misc{census_counties_in_idaho_by_2021,
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), 2021}},
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=2021. 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), 2021
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=2021
Y2 - 2026/10/12
N1 - Accessed via Invokely, https://invokely.ai/rankings/median-age-july-1-us-counties/idaho-counties?period=2021.
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 -
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=10Questions
Which county has the highest median age on 1 July (US county estimates)?
Adams County, with 54.2 years in 2021, according to the U.S. Census Bureau.
Which county has the lowest median age on 1 July (US county estimates)?
Madison County, with 22.6 years in 2021.
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.
Median age on 1 July (US county estimates): other rankings
Counties in Idaho: more rankings
- Black or African American population share
- Crude birth rate, July to June
- Deaths, July to June
- Net domestic migration, July to June
- Median gross rent (monthly)
- Physical inactivity in adults, local model estimate
- Uninsured rate, ages 18 to 64 (US model-based estimate)
- Fair Market Rent, one bedroom (HUD, monthly)