Data / Rankings / Population density / Counties in Iowa

Counties in Iowa by population density, 2025

Polk County had the highest population density of 99 counties in 2025, at 348.2 inhabitants per km². Adams County had the lowest, at 3.3 inhabitants per km². The median was 10 inhabitants per km² and the figure for Iowa was 22.4 inhabitants per km². Source: the U.S. Census Bureau.

Highest348.2Polk County
Lowest3.3Adams County
Median1099 counties
Iowa22.4History

Top 40 counties, 2025

CSVChart (SVG)

Polk CountyPolk County: 348.2 inhabitants per km²348.2Scott CountyScott County: 147.7 inhabitants per km²147.7Linn CountyLinn County: 124.9 inhabitants per km²124.9Johnson CountyJohnson County: 100.8 inhabitants per km²100.8Black Hawk CountyBlack Hawk County: 89.8 inhabitants per km²89.8Dallas CountyDallas County: 77.8 inhabitants per km²77.8Story CountyStory County: 68.3 inhabitants per km²68.3Dubuque CountyDubuque County: 63.1 inhabitants per km²63.1Woodbury CountyWoodbury County: 47.2 inhabitants per km²47.2Warren CountyWarren County: 38.9 inhabitants per km²38.9Pottawattamie CountyPottawattamie County: 37.7 inhabitants per km²37.7Muscatine CountyMuscatine County: 36.9 inhabitants per km²36.9Des Moines CountyDes Moines County: 35.3 inhabitants per km²35.3Wapello CountyWapello County: 31.5 inhabitants per km²31.5Cerro Gordo CountyCerro Gordo County: 28.8 inhabitants per km²28.8Marshall CountyMarshall County: 26.9 inhabitants per km²26.9Clinton CountyClinton County: 25.6 inhabitants per km²25.6Lee CountyLee County: 24.1 inhabitants per km²24.1Marion CountyMarion County: 23.8 inhabitants per km²23.8Bremer CountyBremer County: 22.4 inhabitants per km²22.4Jasper CountyJasper County: 20.2 inhabitants per km²20.2Webster CountyWebster County: 19.9 inhabitants per km²19.9Sioux CountySioux County: 18.5 inhabitants per km²18.5Dickinson CountyDickinson County: 18.3 inhabitants per km²18.3Boone CountyBoone County: 18.1 inhabitants per km²18.1Henry CountyHenry County: 17.2 inhabitants per km²17.2Washington CountyWashington County: 15.4 inhabitants per km²15.4Mahaska CountyMahaska County: 14.8 inhabitants per km²14.8Jones CountyJones County: 14.3 inhabitants per km²14.3Buchanan CountyBuchanan County: 14.1 inhabitants per km²14.1Benton CountyBenton County: 14 inhabitants per km²14Carroll CountyCarroll County: 13.8 inhabitants per km²13.8Buena Vista CountyBuena Vista County: 13.7 inhabitants per km²13.7Jefferson CountyJefferson County: 13.6 inhabitants per km²13.6Mills CountyMills County: 13.1 inhabitants per km²13.1Cedar CountyCedar County: 12.2 inhabitants per km²12.2Poweshiek CountyPoweshiek County: 12.1 inhabitants per km²12.1Madison CountyMadison County: 11.9 inhabitants per km²11.9Delaware CountyDelaware County: 11.8 inhabitants per km²11.8Jackson CountyJackson County: 11.7 inhabitants per km²11.7
inhabitants per km². Source: Invokely calculation with data from U.S. Census Bureau. Retrieved 2026-10-09.

Full ranking

RankCounties2025
inhabitants per km²		Change on 2024
1Polk County348.2+0.6%
2Scott County147.7+0.2%
3Linn County124.9+0.7%
4Johnson County100.8+0.7%
5Black Hawk County89.80%
6Dallas County77.8+3.2%
7Story County68.3-0.1%
8Dubuque County63.1+0.4%
9Woodbury County47.2-0.1%
10Warren County38.9+1.5%
11Pottawattamie County37.7-0.3%
12Muscatine County36.9-0.7%
13Des Moines County35.3-0.2%
14Wapello County31.5-0.6%
15Cerro Gordo County28.8+0.1%
16Marshall County26.9-0.6%
17Clinton County25.60%
18Lee County24.1-0.5%
19Marion County23.8+0.7%
20Bremer County22.4-0.3%
21Jasper County20.2+0.1%
22Webster County19.9+0.1%
23Sioux County18.5-0%
24Dickinson County18.30%
25Boone County18.1+0.3%
26Henry County17.2-0.1%
27Washington County15.4+0.3%
28Mahaska County14.8-0.1%
29Jones County14.3+0.4%
30Buchanan County14.1+0.8%
31Benton County14+0.6%
32Carroll County13.8-0.7%
33Buena Vista County13.7-1%
34Jefferson County13.6-0.7%
35Mills County13.1+0.3%
36Cedar County12.2+0.4%
37Poweshiek County12.1-0.3%
38Madison County11.9+0.7%
39Delaware County11.8+0.4%
40Jackson County11.7-0.3%
41Plymouth County11.5+0.1%
42Floyd County11.5-1.2%
43Hardin County11.2-0%
44Winneshiek County11+0.3%
45Clay County11-1.9%
46Iowa County10.9+0.2%
47Union County10.8-0.8%
48Page County10.7-1%
49Fayette County10.1-0.3%
50Louisa County10-1.4%
51Hamilton County10-0.4%
52Winnebago County9.9-1%
53O'Brien County9.6+0.2%
54Grundy County9.5-0.1%
55Appanoose County9.4-0.2%
56Butler County9.4-0.3%
57Montgomery County9.1-0.5%
58Tama County9-0.1%
59Chickasaw County8.9-0.5%
60Emmet County8.9-0.3%
61Cass County8.9-0.3%
62Crawford County8.8-0.3%
63Mitchell County8.8+0.6%
64Allamakee County8.6+0.2%
65Clarke County8.6-0.2%
66Wright County8.5-0.4%
67Humboldt County8.4-1%
68Clayton County8.4-0.8%
69Lyon County8.1-0.4%
70Harrison County8.1+0.2%
71Lucas County7.9+0.2%
72Howard County7.7-0.2%
73Shelby County7.6-0.8%
74Cherokee County7.6-1.3%
75Hancock County7.1-0.9%
76Davis County7.1+0.6%
77Worth County7.1+0.5%
78Guthrie County7+0.9%
79Monroe County6.6+0.2%
80Franklin County6.5-1.1%
81Keokuk County6.5-0.1%
82Calhoun County6.5-0.9%
83Sac County6.4-0.9%
84Palo Alto County6.1+0.1%
85Ida County6.1+0.1%
86Greene County5.90%
87Osceola County5.8-0.5%
88Kossuth County5.7-1%
89Van Buren County5.7-0.8%
90Decatur County5.6-0.3%
91Adair County5-0.8%
92Wayne County5+1.6%
93Fremont County4.9+0.4%
94Audubon County4.8-0.7%
95Monona County4.8+0.6%
96Pocahontas County4.6-1.5%
97Taylor County4.2-0.1%
98Ringgold County3.3-0.1%
99Adams County3.3+0.5%

Other periods

About this ranking

Resident population divided by land area in km². World Bank figures use mid-year population and land area excluding inland water.

United States: Census Bureau population estimates for 1 July divided by land area (water excluded) from the latest Census Gazetteer files. US tables often give people per square mile; multiply persons per km² by 2.59 to compare.

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 resident population on 1 July divided by land area from the latest Census Gazetteer files, persons per km². https://www2.census.gov/programs-surveys/popest/datasets/2020-2025/. Retrieved 2026-10-09.

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Questions

Which county has the highest population density?

Polk County, with 348.2 inhabitants per km² in 2025, according to the U.S. Census Bureau.

Which county has the lowest population density?

Adams County, with 3.3 inhabitants per km² in 2025.

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 resident population on 1 July divided by land area from the latest Census Gazetteer files, persons per km². Retrieved 2026-10-09.

Population density: other rankings

Counties in Iowa: more rankings