RANKING · 2020 CENSUS · 99 SHOWN OF 99

Most densely populated, Iowa counties · 2020

Iowa counties ranked by residents per square mile (2020). This list covers the 99 counties in Iowa that qualify, ranked against each other statewide. The median across all 99 is 27.

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SAME RANKING BYCities States Metros

RELATEDLargest by population Fastest growing Fastest shrinking Most population gained Most population lost Most sparsely populated

YEAR1990 2000 2010 2020 2025

RANKPLACESTATEPOPPOPULATION DENSITYVS 2000

01Polk County, IAIA516,546860+31%

02Scott County, IAIA175,259381+10%

03Linn County, IAIA232,028321+20%

04Johnson County, IAIA160,044249+38%

05Black Hawk County, IAIA131,532232+2%

06Story County, IAIA101,291172+23%

07Dallas County, IAIA118,457169+145%

08Dubuque County, IAIA99,381163+11%

09Woodbury County, IAIA106,649121+2%

10Muscatine County, IAIA41,85399+4%

11Pottawattamie County, IAIA92,99698+7%

12Des Moines County, IAIA38,07794−8%

13Warren County, IAIA57,33192+29%

14Wapello County, IAIA35,21082−2%

15Cerro Gordo County, IAIA42,37276−7%

16Marshall County, IAIA39,89070+2%

17Clinton County, IAIA46,00267−7%

18Lee County, IAIA32,30665−12%

19Marion County, IAIA34,19260+4%

20Bremer County, IAIA25,29657+7%

21Jasper County, IAIA38,15352+2%

22Webster County, IAIA36,83852−8%

23Henry County, IAIA19,34947+1%

24Boone County, IAIA26,79947+2%

25Sioux County, IAIA36,77447+14%

26Dickinson County, IAIA18,07747+8%

27Washington County, IAIA22,66740+9%

28Mahaska County, IAIA21,88039−1%

29Carroll County, IAIA20,30336−3%

30Buena Vista County, IAIA20,44936+2%

31Buchanan County, IAIA20,88336−3%

32Jefferson County, IAIA15,29136−3%

33Jones County, IAIA21,25336+2%

34Benton County, IAIA26,00436+1%

35Mills County, IAIA14,793330%

36Cedar County, IAIA18,35932+2%

37Poweshiek County, IAIA18,36832−1%

38Floyd County, IAIA14,90131−8%

39Jackson County, IAIA19,28831−4%

40Delaware County, IAIA17,67430−5%

41Plymouth County, IAIA25,69730+3%

42Hardin County, IAIA16,45530−10%

43Madison County, IAIA17,27029+18%

44Winneshiek County, IAIA19,73329−6%

45Clay County, IAIA16,20229−6%

46Union County, IAIA11,82929−1%

47Page County, IAIA14,85628−10%

48Iowa County, IAIA16,50428+6%

49Louisa County, IAIA10,41627−11%

50Fayette County, IAIA19,04727−11%

51Winnebago County, IAIA10,25127−9%

52Hamilton County, IAIA14,94426−9%

53Appanoose County, IAIA12,07725−10%

54O'Brien County, IAIA14,22025−6%

55Butler County, IAIA14,04925−6%

56Grundy County, IAIA12,361250%

57Montgomery County, IAIA10,00224−12%

58Chickasaw County, IAIA11,66324−8%

59Tama County, IAIA16,79624−5%

60Emmet County, IAIA9,10724−15%

61Cass County, IAIA12,96023−11%

62Crawford County, IAIA16,23723−2%

63Clarke County, IAIA9,57423+7%

64Mitchell County, IAIA10,65023−3%

65Wright County, IAIA12,80122−10%

66Humboldt County, IAIA9,40922−8%

67Allamakee County, IAIA14,23822−4%

68Clayton County, IAIA16,84522−9%

69Harrison County, IAIA14,62321−7%

70Lyon County, IAIA12,35420+1%

71Cherokee County, IAIA11,36920−11%

72Lucas County, IAIA8,84720−8%

73Howard County, IAIA9,41520−5%

74Shelby County, IAIA11,68920−11%

75Hancock County, IAIA10,52819−11%

76Worth County, IAIA7,33819−6%

77Davis County, IAIA9,23018+7%

78Guthrie County, IAIA10,78218−6%

79Monroe County, IAIA7,40617−5%

80Calhoun County, IAIA9,56217−11%

81Keokuk County, IAIA9,79717−12%

82Franklin County, IAIA9,86817−6%

83Sac County, IAIA9,52517−15%

84Ida County, IAIA6,77716−11%

85Palo Alto County, IAIA8,89916−11%

86Osceola County, IAIA5,98016−12%

87Greene County, IAIA8,65815−15%

88Kossuth County, IAIA14,32215−14%

89Van Buren County, IAIA7,13115−8%

90Decatur County, IAIA7,65514−12%

91Adair County, IAIA7,40313−9%

92Fremont County, IAIA6,52213−18%

93Audubon County, IAIA5,50913−17%

94Monona County, IAIA8,53913−13%

95Wayne County, IAIA6,73812−3%

96Pocahontas County, IAIA6,81912−18%

97Taylor County, IAIA5,83511−15%

98Adams County, IAIA3,6179−17%

99Ringgold County, IAIA4,6429−15%

SHOWING 1–99 OF 99

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UPDATED 2026-09-11 · DATA: US CENSUS BUREAU DECENNIAL CENSUS