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 2016, at 71.7%. Ringgold County had the lowest, at 51.5%. The median was 56.8% and the figure for Iowa was 60%. Source: the U.S. Census Bureau.

Highest71.7Story County
Lowest51.5Ringgold County
Median56.899 counties
Iowa60History

Top 40 counties, 2016

Story County: 71.7 %Story County71.7Johnson County: 68.7 %Johnson County68.7Black Hawk County: 62.6 %Black Hawk County62.6Polk County: 62.2 %Polk County62.2Winneshiek County: 61.6 %Winneshiek County61.6Linn County: 61.1 %Linn County61.1Scott County: 60.6 %Scott County60.6Webster County: 60.5 %Webster County60.5Dubuque County: 60 %Dubuque County60Pottawattamie County: 59.9 %Pottawattamie County59.9Henry County: 59.9 %Henry County59.9Jefferson County: 59.8 %Jefferson County59.8Dallas County: 59.8 %Dallas County59.8Poweshiek County: 59.8 %Poweshiek County59.8Wapello County: 59.5 %Wapello County59.5Woodbury County: 59.4 %Woodbury County59.4Buena Vista County: 59.4 %Buena Vista County59.4Muscatine County: 58.9 %Muscatine County58.9Decatur County: 58.9 %Decatur County58.9Boone County: 58.9 %Boone County58.9Jones County: 58.8 %Jones County58.8Jasper County: 58.8 %Jasper County58.8Louisa County: 58.8 %Louisa County58.8Warren County: 58.8 %Warren County58.8Benton County: 58.8 %Benton County58.8Winnebago County: 58.7 %Winnebago County58.7Cerro Gordo County: 58.7 %Cerro Gordo County58.7Worth County: 58.4 %Worth County58.4Iowa County: 58.3 %Iowa County58.3Lee County: 58.3 %Lee County58.3Mills County: 58.2 %Mills County58.2Marion County: 58.2 %Marion County58.2Bremer County: 58.2 %Bremer County58.2Cedar County: 58.1 %Cedar County58.1Clinton County: 58.1 %Clinton County58.1Mahaska County: 57.9 %Mahaska County57.9Des Moines County: 57.7 %Des Moines County57.7Jackson County: 57.7 %Jackson County57.7Sioux County: 57.7 %Sioux County57.7Page County: 57.6 %Page County57.6
%. Source: Invokely calculation with data from U.S. Census Bureau. Retrieved 2026-10-12.

Full ranking

RankCounties2016 (%)Change on 2015
1Story County71.7-0.3 pts
2Johnson County68.7-0.4 pts
3Black Hawk County62.6-0.4 pts
4Polk County62.2-0.3 pts
5Winneshiek County61.6-0.7 pts
6Linn County61.1-0.3 pts
7Scott County60.6-0.5 pts
8Webster County60.5-0.3 pts
9Dubuque County60-0.3 pts
10Pottawattamie County59.9-0.5 pts
11Henry County59.9+0.3 pts
12Jefferson County59.8-1.7 pts
13Dallas County59.8+0.1 pts
14Poweshiek County59.8-0.6 pts
15Wapello County59.5-0.5 pts
16Woodbury County59.4-0.3 pts
17Buena Vista County59.4-0.7 pts
18Muscatine County58.9-0.3 pts
19Decatur County58.9-1 pts
20Boone County58.9-0.3 pts
21Jones County58.8-0.5 pts
22Jasper County58.8-0.3 pts
23Louisa County58.8-0.1 pts
24Warren County58.8-0.4 pts
25Benton County58.8-0.2 pts
26Winnebago County58.7-0 pts
27Cerro Gordo County58.7-0.5 pts
28Worth County58.4-0.1 pts
29Iowa County58.3-0.1 pts
30Lee County58.3-0.4 pts
31Mills County58.2-0.2 pts
32Marion County58.2-0.3 pts
33Bremer County58.2-0.5 pts
34Cedar County58.1-0.1 pts
35Clinton County58.1-0.3 pts
36Mahaska County57.9-0.6 pts
37Des Moines County57.7-0.3 pts
38Jackson County57.7-0.3 pts
39Sioux County57.7-0.4 pts
40Page County57.6-0.2 pts
41Union County57.5-0.1 pts
42Delaware County57.5-0.4 pts
43Fayette County57.4-0.7 pts
44Osceola County57.3+0.1 pts
45Clay County57.2-0.2 pts
46Calhoun County57.1-0.1 pts
47Harrison County56.9-0.7 pts
48Madison County56.9-0.1 pts
49Hamilton County56.9-0.3 pts
50Plymouth County56.8-0.4 pts
51Tama County56.6-0.3 pts
52Marshall County56.5-0.5 pts
53Humboldt County56.4-0.5 pts
54Franklin County56.4-0.3 pts
55Monroe County56.3-0.4 pts
56Adair County56.3-0.3 pts
57Chickasaw County56.3-0.5 pts
58Carroll County56.3-0.2 pts
59Emmet County56.3-1 pts
60Crawford County56.2-0.2 pts
61Montgomery County56.2-0.3 pts
62Hardin County56.2-0.1 pts
63Fremont County56.1+0.2 pts
64Clarke County56.1-1.3 pts
65Clayton County56.1-0.3 pts
66Keokuk County56.1-0.1 pts
67Appanoose County56-0.2 pts
68Washington County56-0.3 pts
69Buchanan County56-0.2 pts
70Lucas County56+0.1 pts
71Hancock County55.7-0.4 pts
72O'Brien County55.7-0 pts
73Kossuth County55.6-0.2 pts
74Dickinson County55.6-0.5 pts
75Floyd County55.6-0.2 pts
76Cherokee County55.6-0.4 pts
77Allamakee County55.5-0.6 pts
78Adams County55.5-0.7 pts
79Grundy County55.4-0.7 pts
80Shelby County55.3-0.2 pts
81Van Buren County55.3-0.3 pts
82Palo Alto County55.3-0.5 pts
83Greene County55.2-0 pts
84Sac County55.1+0.1 pts
85Audubon County55-0.2 pts
86Cass County55-0.5 pts
87Wright County55-0.4 pts
88Pocahontas County54.9-0.3 pts
89Howard County54.8-0.3 pts
90Ida County54.7-0.1 pts
91Butler County54.6-0.2 pts
92Guthrie County54.6-0.7 pts
93Taylor County54.4-0.3 pts
94Monona County54.2-0.3 pts
95Wayne County53.9-0.2 pts
96Lyon County53.8-0.5 pts
97Davis County53.70 pts
98Mitchell County53.5-0.4 pts
99Ringgold County51.5-0.2 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, 2016) [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, 2016. 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=2016. 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, 2016. 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=2016.

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, 2016 [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=2016 (Accessed: 12 October 2026).

BibTeX
@misc{census_counties_in_iowa_by_2016,
  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, 2016}},
  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=2016. 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, 2016
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=2016
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/population-18-64/iowa-counties?period=2016.
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 71.7% in 2016, according to the U.S. Census Bureau.

Which county has the lowest population aged 18 to 64?

Ringgold County, with 51.5% in 2016.

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