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 2018, at 70.6%. Ringgold County had the lowest, at 51.3%. The median was 56.3% and the figure for Iowa was 59.4%. Source: the U.S. Census Bureau.

Highest70.6Story County
Lowest51.3Ringgold County
Median56.399 counties
Iowa59.4History

Top 40 counties, 2018

Story County: 70.6 %Story County70.6Johnson County: 67.8 %Johnson County67.8Polk County: 61.8 %Polk County61.8Black Hawk County: 61.4 %Black Hawk County61.4Linn County: 60.6 %Linn County60.6Winneshiek County: 60.3 %Winneshiek County60.3Scott County: 60.1 %Scott County60.1Webster County: 59.8 %Webster County59.8Dallas County: 59.8 %Dallas County59.8Henry County: 59.7 %Henry County59.7Dubuque County: 59.3 %Dubuque County59.3Poweshiek County: 59.2 %Poweshiek County59.2Pottawattamie County: 59.1 %Pottawattamie County59.1Woodbury County: 58.9 %Woodbury County58.9Buena Vista County: 58.5 %Buena Vista County58.5Muscatine County: 58.5 %Muscatine County58.5Jasper County: 58.5 %Jasper County58.5Warren County: 58.3 %Warren County58.3Benton County: 58.3 %Benton County58.3Wapello County: 58.3 %Wapello County58.3Jones County: 58.3 %Jones County58.3Boone County: 58 %Boone County58Louisa County: 58 %Louisa County58Worth County: 57.7 %Worth County57.7Winnebago County: 57.7 %Winnebago County57.7Marion County: 57.7 %Marion County57.7Cerro Gordo County: 57.7 %Cerro Gordo County57.7Clinton County: 57.6 %Clinton County57.6Decatur County: 57.6 %Decatur County57.6Iowa County: 57.5 %Iowa County57.5Cedar County: 57.4 %Cedar County57.4Bremer County: 57.2 %Bremer County57.2Mahaska County: 57.2 %Mahaska County57.2Des Moines County: 57.2 %Des Moines County57.2Fayette County: 57 %Fayette County57Mills County: 57 %Mills County57Madison County: 57 %Madison County57Jackson County: 56.9 %Jackson County56.9Lee County: 56.9 %Lee County56.9Union County: 56.9 %Union County56.9
%. Source: Invokely calculation with data from U.S. Census Bureau. Retrieved 2026-10-12.

Full ranking

RankCounties2018 (%)Change on 2017
1Story County70.6-0.7 pts
2Johnson County67.8-0.4 pts
3Polk County61.8-0.1 pts
4Black Hawk County61.4-0.6 pts
5Linn County60.6-0.2 pts
6Winneshiek County60.3-0.7 pts
7Scott County60.1-0.3 pts
8Webster County59.8-0.3 pts
9Dallas County59.8+0.1 pts
10Henry County59.7-0.4 pts
11Dubuque County59.3-0.2 pts
12Poweshiek County59.2-0.2 pts
13Pottawattamie County59.1-0.3 pts
14Woodbury County58.9-0.2 pts
15Buena Vista County58.5-0.2 pts
16Muscatine County58.5-0.3 pts
17Jasper County58.50 pts
18Warren County58.3-0.4 pts
19Benton County58.3-0.1 pts
20Wapello County58.3-0.7 pts
21Jones County58.3-0.2 pts
22Boone County58-0.5 pts
23Louisa County58-0.6 pts
24Worth County57.7-0.4 pts
25Winnebago County57.7-0.3 pts
26Marion County57.7-0.3 pts
27Cerro Gordo County57.7-0.4 pts
28Clinton County57.6-0.2 pts
29Decatur County57.6-0.6 pts
30Iowa County57.5-0.2 pts
31Cedar County57.4-0.1 pts
32Bremer County57.2-0.4 pts
33Mahaska County57.2-0.5 pts
34Des Moines County57.2-0.4 pts
35Fayette County57-0.2 pts
36Mills County57-0.6 pts
37Madison County57-0 pts
38Jackson County56.9-0 pts
39Lee County56.9-0.5 pts
40Union County56.9-0.3 pts
41Sioux County56.9-0.3 pts
42Page County56.9-0.5 pts
43Delaware County56.8-0.6 pts
44Hamilton County56.7-0.2 pts
45Jefferson County56.4-1.6 pts
46Osceola County56.4-0.9 pts
47Calhoun County56.4-0.3 pts
48Harrison County56.3-0.3 pts
49Plymouth County56.3-0.3 pts
50Clay County56.3-0.7 pts
51Emmet County56.1-0.2 pts
52Marshall County56-0.2 pts
53Crawford County55.9-0.4 pts
54Tama County55.9-0.2 pts
55Buchanan County55.7+0.1 pts
56Adair County55.6-0.4 pts
57Washington County55.6-0.3 pts
58Montgomery County55.6-0.2 pts
59Monroe County55.5-0.1 pts
60Franklin County55.5-0.4 pts
61Keokuk County55.4-0.5 pts
62Adams County55.4-0.2 pts
63Chickasaw County55.4-0.5 pts
64Carroll County55.3-0.4 pts
64O'Brien County55.3-0.3 pts
66Grundy County55.3-0.3 pts
67Clarke County55.2-0.7 pts
68Hardin County55.2-0.8 pts
69Clayton County55.1-0.7 pts
70Humboldt County55.1-0.3 pts
71Shelby County55.1+0.1 pts
72Appanoose County55.1-0.6 pts
73Kossuth County55-0.3 pts
74Lucas County54.9-0.9 pts
75Fremont County54.9-0.4 pts
76Hancock County54.9-0.5 pts
77Floyd County54.8-0.5 pts
78Cass County54.7-0.3 pts
79Palo Alto County54.7-0.6 pts
80Greene County54.6-0.2 pts
81Audubon County54.6-0.3 pts
82Wright County54.3-0 pts
83Dickinson County54.3-0.9 pts
84Pocahontas County54.3-0.5 pts
85Cherokee County54.3-0.5 pts
86Allamakee County54.2-0.6 pts
87Guthrie County54.2-0.4 pts
88Sac County54.2-0.5 pts
89Butler County54.1-0.1 pts
90Van Buren County54-0.8 pts
91Howard County53.9-0.3 pts
92Mitchell County53.7+0.1 pts
93Taylor County53.7-0.6 pts
94Ida County53.6-0.5 pts
95Monona County53.5-0.5 pts
96Lyon County53.3-0.3 pts
97Wayne County53.2-0.2 pts
98Davis County53.1-0.5 pts
99Ringgold County51.3+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, 2018) [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, 2018. 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=2018. 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, 2018. 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=2018.

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, 2018 [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=2018 (Accessed: 12 October 2026).

BibTeX
@misc{census_counties_in_iowa_by_2018,
  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, 2018}},
  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=2018. 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, 2018
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=2018
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/population-18-64/iowa-counties?period=2018.
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 70.6% in 2018, according to the U.S. Census Bureau.

Which county has the lowest population aged 18 to 64?

Ringgold County, with 51.3% in 2018.

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