Data / Population under 18 / Marion County

Population under 18 in Marion County

Population under 18 in Marion County was 22.2% in 2025, according to the U.S. Census Bureau. That is down 0.4 pts from 2024. That is the 47th highest of 99 counties in 2025.

202522.2%
Change on 2024-0.4 pts
Rank47th of 99Counties in Iowa ranked
Series high252010
Series low22.22025

Next release: Friday, 25 June 2027, estimated by Invokely from past publication dates (low confidence), not announced by the publisher. Release calendar

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Population under 18 in Marion County, 2010 to 2025

222324252010201320162019202220252010: 25 %2011: 24.7 %2012: 24.4 %2013: 24.3 %2014: 24.1 %2015: 24.1 %2016: 24 %2017: 23.8 %2018: 23.6 %2019: 23.5 %2020: 23.2 %2021: 23.1 %2022: 23 %2023: 22.9 %2024: 22.6 %2025: 22.2 %222324252010201620252010: 25 %2011: 24.7 %2012: 24.4 %2013: 24.3 %2014: 24.1 %2015: 24.1 %2016: 24 %2017: 23.8 %2018: 23.6 %2019: 23.5 %2020: 23.2 %2021: 23.1 %2022: 23 %2023: 22.9 %2024: 22.6 %2025: 22.2 %
%. Source: Invokely calculation with data from U.S. Census Bureau. Retrieved 2026-10-12, published 2026-06-25.
All 16 values
Period%
202522.2
202422.6
202322.9
202223
202123.1
202023.2
201923.5
201823.6
201723.8
201624
201524.1
201424.1
201324.3
201224.4
201124.7
201025

Compared with Iowa and United States

Place2025
Marion County22.2
Iowa22.2
United States21.1

Marion County compared with nearby places

Adair County: 21.8 %Adams County: 21.5 %Allamakee County: 23.7 %Appanoose County: 20.8 %Audubon County: 22 %Benton County: 22.8 %Black Hawk County: 21.7 %Boone County: 20.7 %Bremer County: 22.1 %Buchanan County: 25.5 %Buena Vista County: 25.3 %Butler County: 21.4 %Calhoun County: 21.3 %Carroll County: 23.3 %Cass County: 22.1 %Cedar County: 20.8 %Cerro Gordo County: 19.5 %Cherokee County: 22.6 %Chickasaw County: 22.6 %Clarke County: 24.1 %Clay County: 21.5 %Clayton County: 21.4 %Clinton County: 22.4 %Crawford County: 25.4 %Dallas County: 25.5 %Davis County: 30 %Decatur County: 22 %Delaware County: 22.6 %Des Moines County: 20.8 %Dickinson County: 18.3 %Dubuque County: 21.6 %Emmet County: 20.5 %Fayette County: 20.6 %Floyd County: 22.7 %Franklin County: 23.8 %Fremont County: 21.7 %Greene County: 21.6 %Grundy County: 23.7 %Guthrie County: 21.4 %Hamilton County: 23.7 %Hancock County: 21.4 %Hardin County: 20.3 %Harrison County: 22.6 %Henry County: 20.4 %Howard County: 24 %Humboldt County: 22.9 %Ida County: 22.6 %Iowa County: 22.1 %Jackson County: 21.3 %Jasper County: 21.4 %Jefferson County: 17.9 %Johnson County: 19 %Jones County: 20.1 %Keokuk County: 22.7 %Kossuth County: 21.7 %Lee County: 21.6 %Linn County: 21.9 %Louisa County: 20.9 %Lucas County: 24.2 %Lyon County: 26.8 %Madison County: 24 %Mahaska County: 23 %Marion County: 22.2 %Marshall County: 24.7 %Mills County: 23 %Mitchell County: 23.5 %Monona County: 21.1 %Monroe County: 22.5 %Montgomery County: 21.6 %Muscatine County: 22.4 %O'Brien County: 23.8 %Osceola County: 20.5 %Page County: 18.8 %Palo Alto County: 22.5 %Plymouth County: 24.4 %Pocahontas County: 22.2 %Polk County: 23.3 %Pottawattamie County: 21.8 %Poweshiek County: 18.9 %Ringgold County: 21.8 %Sac County: 22 %Scott County: 22 %Shelby County: 22.3 %Sioux County: 26.5 %Story County: 15.9 %Tama County: 23.4 %Taylor County: 23 %Union County: 21.2 %Van Buren County: 23.7 %Wapello County: 23 %Warren County: 24 %Washington County: 24.1 %Wayne County: 26.4 %Webster County: 21.3 %Winnebago County: 20.4 %Winneshiek County: 18.4 %Woodbury County: 24.9 %Worth County: 22.1 %Wright County: 24.6 %
  • Under 21
  • 21 to 22
  • 22 to 23
  • 23 to 24
  • 24 and over
Population under 18, 2025, %. Marion County is outlined. Same source and period for every area shown. Source: U.S. Census Bureau. Boundaries: U.S. Census Bureau cartographic boundary files.

Rankings

Definition

Residents aged 0 to 17 as a percentage of total population on 1 July. United States: Census Bureau county population estimates by age; states and the nation are sums of their counties.

Uses the US age of majority. Not comparable with population_0_14_share, which stops at 14.

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How to cite

U.S. Census Bureau. Population Estimates Program, county population by age and sex: residents aged 0 to 17 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties. 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: residents aged 0 to 17 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties (Population under 18, Marion County, 2010 to 2025) [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: residents aged 0 to 17 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties, Population under 18, Marion County, 2010 to 2025. U.S. Census Bureau, 25 June 2026, https://www.census.gov/programs-surveys/popest/data/data-sets.html. Invokely, https://invokely.ai/en/population-under-18/marion-county-iowa. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Census Bureau. 2026. Population Estimates Program, county population by age and sex: residents aged 0 to 17 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties. Population under 18, Marion County, 2010 to 2025. Dataset. Accessed October 12, 2026. https://www.census.gov/programs-surveys/popest/data/data-sets.html. Also distributed by Invokely, https://invokely.ai/en/population-under-18/marion-county-iowa.

Harvard

U.S. Census Bureau (2026) Population Estimates Program, county population by age and sex: residents aged 0 to 17 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties, Population under 18, Marion County, 2010 to 2025 [Dataset]. Available at: https://www.census.gov/programs-surveys/popest/data/data-sets.html, via Invokely: https://invokely.ai/en/population-under-18/marion-county-iowa (Accessed: 12 October 2026).

BibTeX
@misc{census_population_under_18_marion_2025,
  author = {{U.S. Census Bureau}},
  title = {{Population Estimates Program, county population by age and sex: residents aged 0 to 17 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties: Population under 18, Marion County, 2010 to 2025}},
  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/en/population-under-18/marion-county-iowa. Publisher attribution: U.S. Census Bureau. Population Estimates Program, county population by age and sex: residents aged 0 to 17 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties. 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: residents aged 0 to 17 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties: Population under 18, Marion County, 2010 to 2025
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/en/population-under-18/marion-county-iowa
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/en/population-under-18/marion-county-iowa.
N1  - Publisher attribution: U.S. Census Bureau. Population Estimates Program, county population by age and sex: residents aged 0 to 17 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties. https://www.census.gov/programs-surveys/popest/data/data-sets.html. Retrieved 2026-10-12.
ER  -
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Questions

What is the population under 18 in Marion County?

Population under 18 in Marion County was 22.2% in 2025, according to the U.S. Census Bureau. That is down 0.4 pts from 2024. That is the 47th highest of 99 counties in 2025.

Where does this figure come from?

U.S. Census Bureau. Population Estimates Program, county population by age and sex: residents aged 0 to 17 as a percentage of the total on 1 July, 2010 to 2019 from the 2010 to 2020 intercensal file and 2020 onwards from the latest vintage; states and the nation summed from counties. Retrieved by Invokely on 2026-10-12.

What was the highest population under 18 in Marion County?

25% in 2010, the highest value since 2010 in this series.

Related statistics for Marion County

All statistics for Marion County | Marion County in figures