Data / Rankings / Population aged 18 to 64 / Counties in Iowa

Counties in Iowa by population aged 18 to 64

Story County had the highest population aged 18 to 64 of 99 counties in 2020, at 70.1%. Ringgold County had the lowest, at 51.6%. The median was 55.3% and the figure for Iowa was 58.7%. Source: the U.S. Census Bureau.

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Highest70.1Story County
Lowest51.6Ringgold County
Median55.399 counties
Iowa58.7History

Map of counties, 2020

Adair County: 54.2 %Adams County: 55.3 %Allamakee County: 53.5 %Appanoose County: 54.2 %Audubon County: 53.4 %Benton County: 57.7 %Black Hawk County: 60.2 %Boone County: 56.9 %Bremer County: 56.3 %Buchanan County: 54.9 %Buena Vista County: 57.4 %Butler County: 53.2 %Calhoun County: 55.6 %Carroll County: 54.3 %Cass County: 53.9 %Cedar County: 56.8 %Cerro Gordo County: 56.3 %Cherokee County: 53.5 %Chickasaw County: 54.7 %Clarke County: 55.3 %Clay County: 55.3 %Clayton County: 53.9 %Clinton County: 56.8 %Crawford County: 55.2 %Dallas County: 60.1 %Davis County: 52 %Decatur County: 56.5 %Delaware County: 55.8 %Des Moines County: 56.2 %Dickinson County: 53.2 %Dubuque County: 58.4 %Emmet County: 54.9 %Fayette County: 55.6 %Floyd County: 54.1 %Franklin County: 54.4 %Fremont County: 54 %Greene County: 53.8 %Grundy County: 54.6 %Guthrie County: 54 %Hamilton County: 55.7 %Hancock County: 53.7 %Hardin County: 54.5 %Harrison County: 55.9 %Henry County: 59.2 %Howard County: 53.8 %Humboldt County: 54.7 %Ida County: 53.7 %Iowa County: 56.8 %Jackson County: 56.1 %Jasper County: 58.3 %Jefferson County: 53.6 %Johnson County: 67 %Jones County: 57.7 %Keokuk County: 54.4 %Kossuth County: 53.8 %Lee County: 55.8 %Linn County: 60.2 %Louisa County: 57.3 %Lucas County: 54.5 %Lyon County: 52.8 %Madison County: 56.4 %Mahaska County: 56.7 %Marion County: 57.1 %Marshall County: 55.5 %Mills County: 56.3 %Mitchell County: 53.2 %Monona County: 52.8 %Monroe County: 54.9 %Montgomery County: 54.8 %Muscatine County: 57.8 %O'Brien County: 54.6 %Osceola County: 56.2 %Page County: 56 %Palo Alto County: 54 %Plymouth County: 55.7 %Pocahontas County: 53.5 %Polk County: 61.2 %Pottawattamie County: 58.4 %Poweshiek County: 58.9 %Ringgold County: 51.6 %Sac County: 53.1 %Scott County: 59.3 %Shelby County: 54.4 %Sioux County: 56.5 %Story County: 70.1 %Tama County: 54.9 %Taylor County: 52.4 %Union County: 56 %Van Buren County: 52.9 %Wapello County: 57.3 %Warren County: 57.6 %Washington County: 54.9 %Wayne County: 52.3 %Webster County: 58.9 %Winnebago County: 57 %Winneshiek County: 58.9 %Woodbury County: 58.5 %Worth County: 55.6 %Wright County: 53.4 %
  • Under 54
  • 54 to 55
  • 55 to 56
  • 56 to 58
  • 58 and over
%, 2020. Source: Invokely calculation with data from U.S. Census Bureau. Boundaries: U.S. Census Bureau cartographic boundary files.

Top 40 counties, 2020

Story County: 70.1 %Story County70.1Johnson County: 67 %Johnson County67Polk County: 61.2 %Polk County61.2Black Hawk County: 60.2 %Black Hawk County60.2Linn County: 60.2 %Linn County60.2Dallas County: 60.1 %Dallas County60.1Scott County: 59.3 %Scott County59.3Henry County: 59.2 %Henry County59.2Winneshiek County: 58.9 %Winneshiek County58.9Poweshiek County: 58.9 %Poweshiek County58.9Webster County: 58.9 %Webster County58.9Woodbury County: 58.5 %Woodbury County58.5Dubuque County: 58.4 %Dubuque County58.4Pottawattamie County: 58.4 %Pottawattamie County58.4Jasper County: 58.3 %Jasper County58.3Muscatine County: 57.8 %Muscatine County57.8Benton County: 57.7 %Benton County57.7Jones County: 57.7 %Jones County57.7Warren County: 57.6 %Warren County57.6Buena Vista County: 57.4 %Buena Vista County57.4Louisa County: 57.3 %Louisa County57.3Wapello County: 57.3 %Wapello County57.3Marion County: 57.1 %Marion County57.1Winnebago County: 57 %Winnebago County57Boone County: 56.9 %Boone County56.9Iowa County: 56.8 %Iowa County56.8Clinton County: 56.8 %Clinton County56.8Cedar County: 56.8 %Cedar County56.8Mahaska County: 56.7 %Mahaska County56.7Sioux County: 56.5 %Sioux County56.5Decatur County: 56.5 %Decatur County56.5Madison County: 56.4 %Madison County56.4Bremer County: 56.3 %Bremer County56.3Mills County: 56.3 %Mills County56.3Cerro Gordo County: 56.3 %Cerro Gordo County56.3Des Moines County: 56.2 %Des Moines County56.2Osceola County: 56.2 %Osceola County56.2Jackson County: 56.1 %Jackson County56.1Union County: 56 %Union County56Page County: 56 %Page County56Story County: 70.1 %Story County70.1Johnson County: 67 %Johnson County67Polk County: 61.2 %Polk County61.2Black Hawk County: 60.2 %Black Hawk County60.2Linn County: 60.2 %Linn County60.2Dallas County: 60.1 %Dallas County60.1Scott County: 59.3 %Scott County59.3Henry County: 59.2 %Henry County59.2Winneshiek County: 58.9 %Winneshiek County58.9Poweshiek County: 58.9 %Poweshiek County58.9Webster County: 58.9 %Webster County58.9Woodbury County: 58.5 %Woodbury County58.5Dubuque County: 58.4 %Dubuque County58.4Pottawattamie County: 58.4 %Pottawattamie County58.4Jasper County: 58.3 %Jasper County58.3Muscatine County: 57.8 %Muscatine County57.8Benton County: 57.7 %Benton County57.7Jones County: 57.7 %Jones County57.7Warren County: 57.6 %Warren County57.6Buena Vista County: 57.4 %Buena Vista County57.4Louisa County: 57.3 %Louisa County57.3Wapello County: 57.3 %Wapello County57.3Marion County: 57.1 %Marion County57.1Winnebago County: 57 %Winnebago County57Boone County: 56.9 %Boone County56.9Iowa County: 56.8 %Iowa County56.8Clinton County: 56.8 %Clinton County56.8Cedar County: 56.8 %Cedar County56.8Mahaska County: 56.7 %Mahaska County56.7Sioux County: 56.5 %Sioux County56.5Decatur County: 56.5 %Decatur County56.5Madison County: 56.4 %Madison County56.4Bremer County: 56.3 %Bremer County56.3Mills County: 56.3 %Mills County56.3Cerro Gordo County: 56.3 %Cerro Gordo County56.3Des Moines County: 56.2 %Des Moines County56.2Osceola County: 56.2 %Osceola County56.2Jackson County: 56.1 %Jackson County56.1Union County: 56 %Union County56Page County: 56 %Page County56
%. Source: Invokely calculation with data from U.S. Census Bureau. Retrieved 2026-10-12.

Full ranking

RankCounties2020 (%)Change on 2019
1Story County70.1-0.2 pts
2Johnson County67-0.4 pts
3Polk County61.2-0.4 pts
4Black Hawk County60.2-0.5 pts
5Linn County60.2-0.2 pts
6Dallas County60.1+0.2 pts
7Scott County59.3-0.4 pts
8Henry County59.2-0.2 pts
9Winneshiek County58.9-0.6 pts
10Poweshiek County58.9-0.2 pts
11Webster County58.9-0.5 pts
12Woodbury County58.5-0.4 pts
13Dubuque County58.4-0.4 pts
14Pottawattamie County58.4-0.6 pts
15Jasper County58.3-0.2 pts
16Muscatine County57.8-0.4 pts
17Benton County57.7-0.3 pts
18Jones County57.7-0.5 pts
19Warren County57.6-0.3 pts
20Buena Vista County57.4-0.4 pts
21Louisa County57.3-0.4 pts
22Wapello County57.3-0.6 pts
23Marion County57.1-0.1 pts
24Winnebago County57-0.5 pts
25Boone County56.9-0.3 pts
26Iowa County56.8-0.5 pts
27Clinton County56.8-0.5 pts
28Cedar County56.8-0.1 pts
29Mahaska County56.7-0.5 pts
30Sioux County56.5-0.1 pts
31Decatur County56.5+0.4 pts
32Madison County56.4-0.4 pts
33Bremer County56.3-0.4 pts
34Mills County56.3-0.4 pts
35Cerro Gordo County56.3-0.6 pts
36Des Moines County56.2-0.5 pts
37Osceola County56.2-0.1 pts
38Jackson County56.1-0.7 pts
39Union County56-0.5 pts
40Page County56-0.4 pts
41Harrison County55.9-0.5 pts
42Delaware County55.8-0.6 pts
43Lee County55.8-0.6 pts
44Hamilton County55.7-0.5 pts
45Plymouth County55.7-0.4 pts
46Fayette County55.6-0.8 pts
47Worth County55.6-1 pts
48Calhoun County55.6-0.5 pts
49Marshall County55.5-0.2 pts
50Clarke County55.3-0 pts
51Clay County55.3-0.4 pts
52Adams County55.3+0.4 pts
53Crawford County55.2-0.3 pts
54Washington County54.9-0.3 pts
55Monroe County54.9-0.4 pts
56Buchanan County54.9-0.5 pts
57Emmet County54.9-0.4 pts
58Tama County54.9-0.7 pts
59Montgomery County54.8-0.6 pts
60Humboldt County54.7-0.2 pts
61Chickasaw County54.7-0.6 pts
62Grundy County54.6-0.5 pts
63O'Brien County54.6-0.5 pts
64Lucas County54.5-0.4 pts
65Hardin County54.5-0.2 pts
66Keokuk County54.4-0.8 pts
67Franklin County54.4-0.3 pts
68Shelby County54.4-0.2 pts
69Carroll County54.3-0.6 pts
70Adair County54.2-0.6 pts
71Appanoose County54.2-0.4 pts
72Floyd County54.1-0.8 pts
73Palo Alto County54-0.2 pts
74Guthrie County54+0.1 pts
75Fremont County54-0.5 pts
76Clayton County53.9-0.7 pts
77Cass County53.9-0.5 pts
78Kossuth County53.8-0.5 pts
79Howard County53.8-0.1 pts
80Greene County53.8-0.7 pts
81Ida County53.7+0.4 pts
82Hancock County53.7-0.4 pts
83Jefferson County53.6-1.5 pts
84Allamakee County53.5-0.3 pts
85Pocahontas County53.5-0.6 pts
86Cherokee County53.5-0.3 pts
87Audubon County53.4-0.6 pts
88Wright County53.4-0.4 pts
89Mitchell County53.2-0.2 pts
90Butler County53.2-0.6 pts
90Dickinson County53.2-0.7 pts
92Sac County53.1-0.3 pts
93Van Buren County52.9-1 pts
94Lyon County52.8-0.4 pts
95Monona County52.8-0.1 pts
96Taylor County52.4-0.5 pts
97Wayne County52.3-1.3 pts
98Davis County52-0.8 pts
99Ringgold County51.6-0.1 pts

Other periods

About this ranking

Residents aged 18 to 64 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.

Not comparable with working-age shares for ages 15 to 64 used in EU and World Bank statistics.

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 18 to 64 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 18 to 64 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 aged 18 to 64, 2020) [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 18 to 64 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 aged 18 to 64, 2020. U.S. Census Bureau, 25 June 2026, https://www.census.gov/programs-surveys/popest/data/data-sets.html. Invokely, https://invokely.ai/rankings/population-18-64/iowa-counties?period=2020. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Census Bureau. 2026. Population Estimates Program, county population by age and sex: residents aged 18 to 64 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 aged 18 to 64, 2020. 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-18-64/iowa-counties?period=2020.

Harvard

U.S. Census Bureau (2026) Population Estimates Program, county population by age and sex: residents aged 18 to 64 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 aged 18 to 64, 2020 [Dataset]. Available at: https://www.census.gov/programs-surveys/popest/data/data-sets.html, via Invokely: https://invokely.ai/rankings/population-18-64/iowa-counties?period=2020 (Accessed: 12 October 2026).

BibTeX
@misc{census_counties_in_iowa_by_2020,
  author = {{U.S. Census Bureau}},
  title = {{Population Estimates Program, county population by age and sex: residents aged 18 to 64 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 aged 18 to 64, 2020}},
  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-18-64/iowa-counties?period=2020. Publisher attribution: U.S. Census Bureau. Population Estimates Program, county population by age and sex: residents aged 18 to 64 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 18 to 64 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 aged 18 to 64, 2020
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-18-64/iowa-counties?period=2020
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/population-18-64/iowa-counties?period=2020.
N1  - Publisher attribution: U.S. Census Bureau. Population Estimates Program, county population by age and sex: residents aged 18 to 64 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

Which county has the highest population aged 18 to 64?

Story County, with 70.1% in 2020, according to the U.S. Census Bureau.

Which county has the lowest population aged 18 to 64?

Ringgold County, with 51.6% in 2020.

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 18 to 64 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 aged 18 to 64: other rankings

Counties in Iowa: more rankings