Data / Rankings / Population under 18 / Counties in Iowa

Counties in Iowa by population under 18

Davis County had the highest population under 18 of 99 counties in 2024, at 29.6%. Story County had the lowest, at 16.1%. The median was 22.4% and the figure for Iowa was 22.5%. Source: the U.S. Census Bureau.

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Highest29.6Davis County
Lowest16.1Story County
Median22.499 counties
Iowa22.5History

Map of counties, 2024

Adair County: 22.3 %Adams County: 21.6 %Allamakee County: 24.1 %Appanoose County: 21.2 %Audubon County: 21.9 %Benton County: 22.9 %Black Hawk County: 21.7 %Boone County: 21.3 %Bremer County: 22.6 %Buchanan County: 25.5 %Buena Vista County: 25.8 %Butler County: 21.7 %Calhoun County: 21.1 %Carroll County: 23.6 %Cass County: 22.1 %Cedar County: 21.1 %Cerro Gordo County: 19.7 %Cherokee County: 22.6 %Chickasaw County: 22.9 %Clarke County: 24.7 %Clay County: 21.9 %Clayton County: 21.9 %Clinton County: 22.6 %Crawford County: 26 %Dallas County: 25.9 %Davis County: 29.6 %Decatur County: 22.2 %Delaware County: 22.7 %Des Moines County: 21 %Dickinson County: 18.6 %Dubuque County: 21.8 %Emmet County: 20.8 %Fayette County: 20.6 %Floyd County: 23.2 %Franklin County: 24 %Fremont County: 21.7 %Greene County: 21.8 %Grundy County: 24 %Guthrie County: 21.2 %Hamilton County: 23.6 %Hancock County: 21.8 %Hardin County: 20.7 %Harrison County: 22.8 %Henry County: 20.4 %Howard County: 24.2 %Humboldt County: 23.2 %Ida County: 22.8 %Iowa County: 22.5 %Jackson County: 21.5 %Jasper County: 21.7 %Jefferson County: 18.1 %Johnson County: 19.2 %Jones County: 20.2 %Keokuk County: 22.9 %Kossuth County: 21.8 %Lee County: 21.5 %Linn County: 22.1 %Louisa County: 21.2 %Lucas County: 24.1 %Lyon County: 27.6 %Madison County: 24.3 %Mahaska County: 23.1 %Marion County: 22.6 %Marshall County: 24.9 %Mills County: 23.4 %Mitchell County: 23.7 %Monona County: 21.3 %Monroe County: 22.6 %Montgomery County: 21.8 %Muscatine County: 22.8 %O'Brien County: 24 %Osceola County: 20.9 %Page County: 19.4 %Palo Alto County: 22.4 %Plymouth County: 24.5 %Pocahontas County: 22.3 %Polk County: 23.6 %Pottawattamie County: 22.3 %Poweshiek County: 18.9 %Ringgold County: 21.9 %Sac County: 22.1 %Scott County: 22.4 %Shelby County: 22.4 %Sioux County: 27 %Story County: 16.1 %Tama County: 23.3 %Taylor County: 23.2 %Union County: 21.6 %Van Buren County: 24.1 %Wapello County: 23.3 %Warren County: 24.5 %Washington County: 24.1 %Wayne County: 26.4 %Webster County: 21.3 %Winnebago County: 20.2 %Winneshiek County: 18.6 %Woodbury County: 25.2 %Worth County: 22.1 %Wright County: 24.8 %
  • Under 21
  • 21 to 22
  • 22 to 23
  • 23 to 24
  • 24 and over
%, 2024. Source: Invokely calculation with data from U.S. Census Bureau. Boundaries: U.S. Census Bureau cartographic boundary files.

Top 40 counties, 2024

Davis County: 29.6 %Davis County29.6Lyon County: 27.6 %Lyon County27.6Sioux County: 27 %Sioux County27Wayne County: 26.4 %Wayne County26.4Crawford County: 26 %Crawford County26Dallas County: 25.9 %Dallas County25.9Buena Vista County: 25.8 %Buena Vista County25.8Buchanan County: 25.5 %Buchanan County25.5Woodbury County: 25.2 %Woodbury County25.2Marshall County: 24.9 %Marshall County24.9Wright County: 24.8 %Wright County24.8Clarke County: 24.7 %Clarke County24.7Warren County: 24.5 %Warren County24.5Plymouth County: 24.5 %Plymouth County24.5Madison County: 24.3 %Madison County24.3Howard County: 24.2 %Howard County24.2Allamakee County: 24.1 %Allamakee County24.1Lucas County: 24.1 %Lucas County24.1Washington County: 24.1 %Washington County24.1Van Buren County: 24.1 %Van Buren County24.1O'Brien County: 24 %O'Brien County24Franklin County: 24 %Franklin County24Grundy County: 24 %Grundy County24Mitchell County: 23.7 %Mitchell County23.7Hamilton County: 23.6 %Hamilton County23.6Carroll County: 23.6 %Carroll County23.6Polk County: 23.6 %Polk County23.6Mills County: 23.4 %Mills County23.4Wapello County: 23.3 %Wapello County23.3Tama County: 23.3 %Tama County23.3Floyd County: 23.2 %Floyd County23.2Humboldt County: 23.2 %Humboldt County23.2Taylor County: 23.2 %Taylor County23.2Mahaska County: 23.1 %Mahaska County23.1Keokuk County: 22.9 %Keokuk County22.9Chickasaw County: 22.9 %Chickasaw County22.9Benton County: 22.9 %Benton County22.9Harrison County: 22.8 %Harrison County22.8Muscatine County: 22.8 %Muscatine County22.8Ida County: 22.8 %Ida County22.8Davis County: 29.6 %Davis County29.6Lyon County: 27.6 %Lyon County27.6Sioux County: 27 %Sioux County27Wayne County: 26.4 %Wayne County26.4Crawford County: 26 %Crawford County26Dallas County: 25.9 %Dallas County25.9Buena Vista County: 25.8 %Buena Vista County25.8Buchanan County: 25.5 %Buchanan County25.5Woodbury County: 25.2 %Woodbury County25.2Marshall County: 24.9 %Marshall County24.9Wright County: 24.8 %Wright County24.8Clarke County: 24.7 %Clarke County24.7Warren County: 24.5 %Warren County24.5Plymouth County: 24.5 %Plymouth County24.5Madison County: 24.3 %Madison County24.3Howard County: 24.2 %Howard County24.2Allamakee County: 24.1 %Allamakee County24.1Lucas County: 24.1 %Lucas County24.1Washington County: 24.1 %Washington County24.1Van Buren County: 24.1 %Van Buren County24.1O'Brien County: 24 %O'Brien County24Franklin County: 24 %Franklin County24Grundy County: 24 %Grundy County24Mitchell County: 23.7 %Mitchell County23.7Hamilton County: 23.6 %Hamilton County23.6Carroll County: 23.6 %Carroll County23.6Polk County: 23.6 %Polk County23.6Mills County: 23.4 %Mills County23.4Wapello County: 23.3 %Wapello County23.3Tama County: 23.3 %Tama County23.3Floyd County: 23.2 %Floyd County23.2Humboldt County: 23.2 %Humboldt County23.2Taylor County: 23.2 %Taylor County23.2Mahaska County: 23.1 %Mahaska County23.1Keokuk County: 22.9 %Keokuk County22.9Chickasaw County: 22.9 %Chickasaw County22.9Benton County: 22.9 %Benton County22.9Harrison County: 22.8 %Harrison County22.8Muscatine County: 22.8 %Muscatine County22.8Ida County: 22.8 %Ida County22.8
%. Source: Invokely calculation with data from U.S. Census Bureau. Retrieved 2026-10-12.

Full ranking

RankCounties2024 (%)Change on 2023
1Davis County29.6-0.3 pts
2Lyon County27.6-0.5 pts
3Sioux County27-0.4 pts
4Wayne County26.4+0.1 pts
5Crawford County26-0.2 pts
6Dallas County25.9-0.5 pts
7Buena Vista County25.8-0.1 pts
8Buchanan County25.5-0.3 pts
9Woodbury County25.2-0.2 pts
10Marshall County24.9-0.3 pts
11Wright County24.8-0.3 pts
12Clarke County24.7-0.3 pts
13Warren County24.5-0.4 pts
14Plymouth County24.5-0.2 pts
15Madison County24.3-0.5 pts
16Howard County24.2-0 pts
17Allamakee County24.10 pts
18Lucas County24.1+0.3 pts
19Washington County24.1-0.1 pts
20Van Buren County24.1-0.3 pts
21O'Brien County24+0.2 pts
22Franklin County24-0 pts
23Grundy County24-0.2 pts
24Mitchell County23.7-0 pts
25Hamilton County23.6+0.3 pts
26Carroll County23.6-0.3 pts
27Polk County23.6-0.2 pts
28Mills County23.4-0.1 pts
29Wapello County23.3-0.3 pts
30Tama County23.3-0.5 pts
31Floyd County23.2-0.2 pts
32Humboldt County23.2-0.4 pts
33Taylor County23.2-0.9 pts
34Mahaska County23.1-0.4 pts
35Keokuk County22.9-0 pts
36Chickasaw County22.9-0 pts
37Benton County22.9-0.2 pts
38Harrison County22.8-0.3 pts
39Muscatine County22.8-0.3 pts
40Ida County22.8-0.4 pts
41Delaware County22.7-0.4 pts
42Cherokee County22.6+0.3 pts
42Marion County22.6-0.3 pts
44Bremer County22.6-0.2 pts
45Monroe County22.6-0.1 pts
46Clinton County22.6-0.1 pts
47Iowa County22.5+0.1 pts
48Palo Alto County22.4+0.1 pts
49Scott County22.4-0.3 pts
50Shelby County22.40 pts
51Pocahontas County22.3-0.4 pts
52Adair County22.3-0.1 pts
53Pottawattamie County22.3-0.4 pts
54Decatur County22.2-0.7 pts
55Cass County22.1-0.2 pts
56Linn County22.1-0.3 pts
57Sac County22.1-0.1 pts
58Worth County22.1-0.1 pts
59Audubon County21.9-0.1 pts
60Ringgold County21.9+0.2 pts
61Clayton County21.9-0 pts
62Clay County21.9-0.4 pts
63Dubuque County21.8-0.2 pts
64Greene County21.80 pts
65Montgomery County21.8-0 pts
66Kossuth County21.8+0.2 pts
67Hancock County21.8+0.1 pts
68Jasper County21.7-0.2 pts
69Fremont County21.7-0.4 pts
70Black Hawk County21.7-0.1 pts
71Butler County21.7-0 pts
72Union County21.6-0.1 pts
73Adams County21.6+0.5 pts
74Lee County21.5+0.1 pts
75Jackson County21.5-0.2 pts
76Boone County21.3-0.6 pts
77Monona County21.3-0.7 pts
78Webster County21.30 pts
79Guthrie County21.2-0.4 pts
80Louisa County21.2-0.1 pts
81Appanoose County21.2-0.2 pts
82Calhoun County21.1-0.2 pts
83Cedar County21.1-0.5 pts
84Des Moines County21-0.3 pts
85Osceola County20.9-0.5 pts
86Emmet County20.8-0.2 pts
87Hardin County20.7-0.4 pts
88Fayette County20.6-0.4 pts
89Henry County20.4-0.3 pts
90Jones County20.2-0.1 pts
91Winnebago County20.2-0.1 pts
92Cerro Gordo County19.7-0.4 pts
93Page County19.4-0.4 pts
94Johnson County19.2-0.2 pts
95Poweshiek County18.9-0.1 pts
96Dickinson County18.6-0.2 pts
97Winneshiek County18.6-0.2 pts
98Jefferson County18.1-0 pts
99Story County16.1-0.2 pts

Other periods

About this ranking

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.

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: 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 (Counties in Iowa by population under 18, 2024) [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, Counties in Iowa by population under 18, 2024. U.S. Census Bureau, 25 June 2026, https://www.census.gov/programs-surveys/popest/data/data-sets.html. Invokely, https://invokely.ai/rankings/population-under-18/iowa-counties?period=2024. 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. Counties in Iowa by population under 18, 2024. Dataset. Accessed October 12, 2026. https://www.census.gov/programs-surveys/popest/data/data-sets.html. Also distributed by Invokely, https://invokely.ai/rankings/population-under-18/iowa-counties?period=2024.

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, Counties in Iowa by population under 18, 2024 [Dataset]. Available at: https://www.census.gov/programs-surveys/popest/data/data-sets.html, via Invokely: https://invokely.ai/rankings/population-under-18/iowa-counties?period=2024 (Accessed: 12 October 2026).

BibTeX
@misc{census_counties_in_iowa_by_2024,
  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: Counties in Iowa by population under 18, 2024}},
  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/population-under-18/iowa-counties?period=2024. 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: Counties in Iowa by population under 18, 2024
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/population-under-18/iowa-counties?period=2024
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/population-under-18/iowa-counties?period=2024.
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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Rank Counties in Iowa by population under 18 using official data, and cite the source.
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Questions

Which county has the highest population under 18?

Davis County, with 29.6% in 2024, according to the U.S. Census Bureau.

Which county has the lowest population under 18?

Story County, with 16.1% in 2024.

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: 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 2026-10-12.

Population under 18: other rankings

Counties in Iowa: more rankings