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 2017, at 29%. Story County had the lowest, at 17%. The median was 23% and the figure for Iowa was 23.5%. Source: the U.S. Census Bureau.

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Highest29Davis County
Lowest17Story County
Median2399 counties
Iowa23.5History

Map of counties, 2017

Adair County: 21.4 %Adams County: 22.1 %Allamakee County: 23.1 %Appanoose County: 21.7 %Audubon County: 20.4 %Benton County: 23.9 %Black Hawk County: 21.9 %Boone County: 23.2 %Bremer County: 22.9 %Buchanan County: 26.8 %Buena Vista County: 25.8 %Butler County: 22.7 %Calhoun County: 21.2 %Carroll County: 24.3 %Cass County: 22.2 %Cedar County: 23.3 %Cerro Gordo County: 20.3 %Cherokee County: 21.4 %Chickasaw County: 23.7 %Clarke County: 25.2 %Clay County: 22.5 %Clayton County: 21.8 %Clinton County: 23.1 %Crawford County: 26.4 %Dallas County: 28.6 %Davis County: 29 %Decatur County: 22.4 %Delaware County: 23.7 %Des Moines County: 22.1 %Dickinson County: 19.2 %Dubuque County: 22.8 %Emmet County: 22.3 %Fayette County: 20.9 %Floyd County: 23.4 %Franklin County: 23.5 %Fremont County: 22.1 %Greene County: 22.7 %Grundy County: 23.7 %Guthrie County: 22.7 %Hamilton County: 22.8 %Hancock County: 22.4 %Hardin County: 22.4 %Harrison County: 23.2 %Henry County: 21.4 %Howard County: 24.8 %Humboldt County: 23.9 %Ida County: 22.9 %Iowa County: 23.4 %Jackson County: 22.1 %Jasper County: 22.6 %Jefferson County: 18.2 %Johnson County: 20.6 %Jones County: 21.7 %Keokuk County: 23.3 %Kossuth County: 21.4 %Lee County: 21.7 %Linn County: 23.9 %Louisa County: 23.3 %Lucas County: 23.2 %Lyon County: 29 %Madison County: 25.6 %Mahaska County: 24.1 %Marion County: 23.8 %Marshall County: 25.4 %Mills County: 24.8 %Mitchell County: 23.9 %Monona County: 21.5 %Monroe County: 24 %Montgomery County: 22.3 %Muscatine County: 24.8 %O'Brien County: 23 %Osceola County: 22.9 %Page County: 21.1 %Palo Alto County: 22.4 %Plymouth County: 25.3 %Pocahontas County: 22.6 %Polk County: 25.1 %Pottawattamie County: 23.8 %Poweshiek County: 19.9 %Ringgold County: 23.6 %Sac County: 22.2 %Scott County: 24 %Shelby County: 22.5 %Sioux County: 27.9 %Story County: 17 %Tama County: 24.2 %Taylor County: 23 %Union County: 22.7 %Van Buren County: 23.3 %Wapello County: 23.4 %Warren County: 25.3 %Washington County: 24.8 %Wayne County: 25.8 %Webster County: 21.4 %Winnebago County: 21.1 %Winneshiek County: 19 %Woodbury County: 26.3 %Worth County: 22.1 %Wright County: 24.4 %
  • Under 21
  • 21 to 22
  • 22 to 23
  • 23 to 24
  • 24 to 25
  • 25 and over
%, 2017. Source: Invokely calculation with data from U.S. Census Bureau. Boundaries: U.S. Census Bureau cartographic boundary files.

Top 40 counties, 2017

Davis County: 29 %Davis County29Lyon County: 29 %Lyon County29Dallas County: 28.6 %Dallas County28.6Sioux County: 27.9 %Sioux County27.9Buchanan County: 26.8 %Buchanan County26.8Crawford County: 26.4 %Crawford County26.4Woodbury County: 26.3 %Woodbury County26.3Buena Vista County: 25.8 %Buena Vista County25.8Wayne County: 25.8 %Wayne County25.8Madison County: 25.6 %Madison County25.6Marshall County: 25.4 %Marshall County25.4Warren County: 25.3 %Warren County25.3Plymouth County: 25.3 %Plymouth County25.3Clarke County: 25.2 %Clarke County25.2Polk County: 25.1 %Polk County25.1Washington County: 24.8 %Washington County24.8Mills County: 24.8 %Mills County24.8Muscatine County: 24.8 %Muscatine County24.8Howard County: 24.8 %Howard County24.8Wright County: 24.4 %Wright County24.4Carroll County: 24.3 %Carroll County24.3Tama County: 24.2 %Tama County24.2Mahaska County: 24.1 %Mahaska County24.1Monroe County: 24 %Monroe County24Scott County: 24 %Scott County24Mitchell County: 23.9 %Mitchell County23.9Humboldt County: 23.9 %Humboldt County23.9Benton County: 23.9 %Benton County23.9Linn County: 23.9 %Linn County23.9Marion County: 23.8 %Marion County23.8Pottawattamie County: 23.8 %Pottawattamie County23.8Delaware County: 23.7 %Delaware County23.7Chickasaw County: 23.7 %Chickasaw County23.7Grundy County: 23.7 %Grundy County23.7Ringgold County: 23.6 %Ringgold County23.6Franklin County: 23.5 %Franklin County23.5Iowa County: 23.4 %Iowa County23.4Floyd County: 23.4 %Floyd County23.4Wapello County: 23.4 %Wapello County23.4Cedar County: 23.3 %Cedar County23.3Davis County: 29 %Davis County29Lyon County: 29 %Lyon County29Dallas County: 28.6 %Dallas County28.6Sioux County: 27.9 %Sioux County27.9Buchanan County: 26.8 %Buchanan County26.8Crawford County: 26.4 %Crawford County26.4Woodbury County: 26.3 %Woodbury County26.3Buena Vista County: 25.8 %Buena Vista County25.8Wayne County: 25.8 %Wayne County25.8Madison County: 25.6 %Madison County25.6Marshall County: 25.4 %Marshall County25.4Warren County: 25.3 %Warren County25.3Plymouth County: 25.3 %Plymouth County25.3Clarke County: 25.2 %Clarke County25.2Polk County: 25.1 %Polk County25.1Washington County: 24.8 %Washington County24.8Mills County: 24.8 %Mills County24.8Muscatine County: 24.8 %Muscatine County24.8Howard County: 24.8 %Howard County24.8Wright County: 24.4 %Wright County24.4Carroll County: 24.3 %Carroll County24.3Tama County: 24.2 %Tama County24.2Mahaska County: 24.1 %Mahaska County24.1Monroe County: 24 %Monroe County24Scott County: 24 %Scott County24Mitchell County: 23.9 %Mitchell County23.9Humboldt County: 23.9 %Humboldt County23.9Benton County: 23.9 %Benton County23.9Linn County: 23.9 %Linn County23.9Marion County: 23.8 %Marion County23.8Pottawattamie County: 23.8 %Pottawattamie County23.8Delaware County: 23.7 %Delaware County23.7Chickasaw County: 23.7 %Chickasaw County23.7Grundy County: 23.7 %Grundy County23.7Ringgold County: 23.6 %Ringgold County23.6Franklin County: 23.5 %Franklin County23.5Iowa County: 23.4 %Iowa County23.4Floyd County: 23.4 %Floyd County23.4Wapello County: 23.4 %Wapello County23.4Cedar County: 23.3 %Cedar County23.3
%. Source: Invokely calculation with data from U.S. Census Bureau. Retrieved 2026-10-12.

Full ranking

RankCounties2017 (%)Change on 2016
1Davis County29+0.2 pts
2Lyon County29+0.1 pts
3Dallas County28.6-0.1 pts
4Sioux County27.9+0.1 pts
5Buchanan County26.8+0.1 pts
6Crawford County26.4-0.1 pts
7Woodbury County26.3-0.1 pts
8Buena Vista County25.8+0.3 pts
9Wayne County25.8+0.2 pts
10Madison County25.6-0.5 pts
11Marshall County25.4+0.1 pts
12Warren County25.3-0.2 pts
13Plymouth County25.3+0.2 pts
14Clarke County25.2+0.1 pts
15Polk County25.1-0 pts
16Washington County24.8-0.1 pts
17Mills County24.8+0.1 pts
18Muscatine County24.8-0.3 pts
19Howard County24.80 pts
20Wright County24.4+0.4 pts
21Carroll County24.3+0.1 pts
22Tama County24.2+0.1 pts
23Mahaska County24.1-0.2 pts
24Monroe County24+0.2 pts
25Scott County24-0.1 pts
26Mitchell County23.9-0.2 pts
27Humboldt County23.9+0.5 pts
28Benton County23.9-0.1 pts
29Linn County23.9-0.1 pts
30Marion County23.8-0.2 pts
31Pottawattamie County23.8-0 pts
32Delaware County23.7-0.2 pts
33Chickasaw County23.7+0.1 pts
34Grundy County23.7-0.3 pts
35Ringgold County23.6+0.1 pts
36Franklin County23.5+0.2 pts
37Iowa County23.4+0.1 pts
38Floyd County23.40 pts
39Wapello County23.4+0.1 pts
40Cedar County23.3+0.1 pts
41Keokuk County23.3-0.1 pts
42Louisa County23.3-0.4 pts
43Van Buren County23.3-0.2 pts
44Boone County23.2-0.1 pts
44Harrison County23.2+0.1 pts
46Lucas County23.2-0.4 pts
47Allamakee County23.1+0.3 pts
48Clinton County23.1+0.1 pts
49O'Brien County23-0.2 pts
50Taylor County23-0.5 pts
51Bremer County22.9+0.4 pts
52Ida County22.9+0.1 pts
53Osceola County22.9-0.1 pts
54Dubuque County22.8-0.1 pts
55Hamilton County22.8-0.3 pts
56Greene County22.70 pts
57Guthrie County22.7-0.4 pts
58Butler County22.7-0.2 pts
59Union County22.7-0.1 pts
60Pocahontas County22.6+0.2 pts
61Jasper County22.6+0.1 pts
62Clay County22.5-0.2 pts
63Shelby County22.5-0 pts
64Palo Alto County22.4-0.1 pts
65Decatur County22.4+0.1 pts
66Hardin County22.4-0.3 pts
67Hancock County22.4-0.1 pts
68Montgomery County22.3-0.1 pts
69Emmet County22.3-0.4 pts
70Sac County22.2+0.1 pts
71Cass County22.2-0.4 pts
72Jackson County22.1+0.1 pts
73Fremont County22.1-0.2 pts
74Des Moines County22.1-0.3 pts
75Worth County22.1-0.1 pts
76Adams County22.10 pts
77Black Hawk County21.9+0.2 pts
78Clayton County21.8-0 pts
79Jones County21.7-0.2 pts
80Appanoose County21.7-0.3 pts
81Lee County21.7+0.2 pts
82Monona County21.5+0.2 pts
83Cherokee County21.4+0.3 pts
84Adair County21.4-0.2 pts
85Webster County21.4+0.1 pts
86Kossuth County21.4-0.2 pts
87Henry County21.4-0.3 pts
88Calhoun County21.2-0.1 pts
89Winnebago County21.10 pts
90Page County21.1-0.3 pts
91Fayette County20.9-0.3 pts
92Johnson County20.6+0.1 pts
93Audubon County20.40 pts
94Cerro Gordo County20.3-0 pts
95Poweshiek County19.9-0.2 pts
96Dickinson County19.2-0.1 pts
97Winneshiek County19-0 pts
98Jefferson County18.2+0.1 pts
99Story County170 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, 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: 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, 2017. 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=2017. 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, 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/population-under-18/iowa-counties?period=2017.

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

BibTeX
@misc{census_counties_in_iowa_by_2017,
  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, 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/population-under-18/iowa-counties?period=2017. 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, 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/population-under-18/iowa-counties?period=2017
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/population-under-18/iowa-counties?period=2017.
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% in 2017, according to the U.S. Census Bureau.

Which county has the lowest population under 18?

Story County, with 17% 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: 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