Data / Rankings / Population density / Counties in Iowa

Counties in Iowa by population density

Polk County had the highest population density of 99 counties in 2024, at 346.2 inhabitants per km². Adams County had the lowest, at 3.3 inhabitants per km². The median was 10.1 inhabitants per km² and the figure for Iowa was 22.3 inhabitants per km². Source: the U.S. Census Bureau.

Highest346.2Polk County
Lowest3.3Adams County
Median10.199 counties
Iowa22.3History

Top 40 counties, 2024

CSVChart (SVG)

Polk CountyPolk County: 346.2 inhabitants per km²346.2Scott CountyScott County: 147.4 inhabitants per km²147.4Linn CountyLinn County: 124.1 inhabitants per km²124.1Johnson CountyJohnson County: 100.1 inhabitants per km²100.1Black Hawk CountyBlack Hawk County: 89.7 inhabitants per km²89.7Dallas CountyDallas County: 75.4 inhabitants per km²75.4Story CountyStory County: 68.4 inhabitants per km²68.4Dubuque CountyDubuque County: 62.9 inhabitants per km²62.9Woodbury CountyWoodbury County: 47.2 inhabitants per km²47.2Warren CountyWarren County: 38.3 inhabitants per km²38.3Pottawattamie CountyPottawattamie County: 37.9 inhabitants per km²37.9Muscatine CountyMuscatine County: 37.2 inhabitants per km²37.2Des Moines CountyDes Moines County: 35.4 inhabitants per km²35.4Wapello CountyWapello County: 31.7 inhabitants per km²31.7Cerro Gordo CountyCerro Gordo County: 28.8 inhabitants per km²28.8Marshall CountyMarshall County: 27.1 inhabitants per km²27.1Clinton CountyClinton County: 25.6 inhabitants per km²25.6Lee CountyLee County: 24.2 inhabitants per km²24.2Marion CountyMarion County: 23.6 inhabitants per km²23.6Bremer CountyBremer County: 22.5 inhabitants per km²22.5Jasper 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: 15.3 inhabitants per km²15.3Mahaska CountyMahaska County: 14.8 inhabitants per km²14.8Jones CountyJones County: 14.2 inhabitants per km²14.2Buchanan CountyBuchanan County: 14 inhabitants per km²14Benton CountyBenton County: 13.9 inhabitants per km²13.9Buena Vista CountyBuena Vista County: 13.9 inhabitants per km²13.9Carroll CountyCarroll County: 13.9 inhabitants per km²13.9Jefferson CountyJefferson County: 13.7 inhabitants per km²13.7Mills CountyMills County: 13 inhabitants per km²13Cedar CountyCedar County: 12.2 inhabitants per km²12.2Poweshiek CountyPoweshiek County: 12.2 inhabitants per km²12.2Madison CountyMadison County: 11.8 inhabitants per km²11.8Delaware 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

RankCounties2024
inhabitants per km²		Change on 2023
1Polk County346.2+1.3%
2Scott County147.4+0.4%
3Linn County124.1+0.7%
4Johnson County100.1+0.7%
5Black Hawk County89.7+0.5%
6Dallas County75.4+3.1%
7Story County68.4+0.4%
8Dubuque County62.9+0.1%
9Woodbury County47.2+0.2%
10Warren County38.3+2.1%
11Pottawattamie County37.9-0.1%
12Muscatine County37.2-0.3%
13Des Moines County35.4-0.4%
14Wapello County31.7+0.1%
15Cerro Gordo County28.8-0.2%
16Marshall County27.1+0.1%
17Clinton County25.6-0.2%
18Lee County24.2-0.1%
19Marion County23.6+0.9%
20Bremer County22.5+0.1%
21Jasper County20.2+0.3%
22Webster County19.9+0.4%
23Sioux County18.5+0.8%
24Dickinson County18.3-0%
25Boone County18.1+0.5%
26Henry County17.2-1.2%
27Washington County15.3+0.2%
28Mahaska County14.8-0.2%
29Jones County14.2+1.1%
30Buchanan County14-0.1%
31Benton County13.9+0.3%
32Buena Vista County13.9-0.1%
33Carroll County13.9-0.3%
34Jefferson County13.7-0.4%
35Mills County13+0.9%
36Cedar County12.2-0%
37Poweshiek County12.2-0.3%
38Madison County11.8+0.8%
39Delaware County11.8+0.2%
40Jackson County11.70%
41Floyd County11.6-1.5%
42Plymouth County11.5-0.2%
43Clay County11.2-0.1%
44Hardin County11.2-0.4%
45Winneshiek County11-0.2%
46Union County10.9+0.3%
47Iowa County10.8+0.3%
48Page County10.8+0.1%
49Louisa County10.2+0.4%
50Fayette County10.1-0.6%
51Hamilton County10+0.6%
52Winnebago County10-1.8%
53O'Brien County9.6+1%
54Grundy County9.5-0.1%
55Appanoose County9.4-0.2%
56Butler County9.4-0.7%
57Montgomery County9.2-1%
58Tama County9-0.1%
59Chickasaw County9+0.1%
60Emmet County8.9-1.8%
61Cass County8.9-0.9%
62Crawford County8.8+1%
63Mitchell County8.7+0.4%
64Clarke County8.6-0.6%
65Allamakee County8.6+0.3%
66Wright County8.5+0.2%
67Humboldt County8.4-0.2%
68Clayton County8.4-0.2%
69Lyon County8.2+0.8%
70Harrison County8.1-0.4%
71Lucas County7.9+0.6%
72Cherokee County7.7-0.6%
73Howard County7.7+0.4%
74Shelby County7.7-0.1%
75Hancock County7.2-0.2%
76Davis County7.1+0.2%
77Worth County7-0.4%
78Guthrie County7-0.5%
79Franklin County6.6+1%
80Monroe County6.6-1.3%
81Calhoun County6.5-1.2%
82Keokuk County6.5-1.3%
83Sac County6.5-0.8%
84Palo Alto County6.1+0.6%
85Ida County6.1-0.7%
86Greene County5.9+0.6%
87Osceola County5.8-0.1%
88Kossuth County5.7+0.1%
89Van Buren County5.7-0.9%
90Decatur County5.6-1.3%
91Adair County5.1+0.6%
92Fremont County4.9+0.5%
93Wayne County4.9+1.3%
94Audubon County4.8+0.4%
95Monona County4.7-0.5%
96Pocahontas County4.6-1%
97Taylor County4.2-1.4%
98Ringgold County3.4-0.3%
99Adams County3.3+1.2%

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 346.2 inhabitants per km² in 2024, according to the U.S. Census Bureau.

Which county has the lowest population density?

Adams County, with 3.3 inhabitants per km² in 2024.

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