RANKING · 2010 CENSUS · 99 SHOWN OF 99

Largest by population, Iowa counties · 2010

The most populous Iowa counties as of the 2010 population estimates. This list covers the 99 counties in Iowa that qualify, ranked against each other statewide.

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SAME RANKING BYCities States Metros ZIP codes

RELATEDFastest growing Fastest shrinking Most population gained Most population lost Most densely populated Most sparsely populated

YEAR1990 2000 2010 2020 2025

RANKPLACESTATETOTAL POPULATIONVS 2000

01Polk County, IAIA430,640+15%

02Linn County, IAIA211,226+10%

03Scott County, IAIA165,224+4%

04Black Hawk County, IAIA131,090+2%

05Johnson County, IAIA130,882+18%

06Woodbury County, IAIA102,172−2%

07Dubuque County, IAIA93,653+5%

08Pottawattamie County, IAIA93,158+6%

09Story County, IAIA89,542+12%

10Dallas County, IAIA66,135+62%

11Clinton County, IAIA49,116−2%

12Warren County, IAIA46,225+14%

13Cerro Gordo County, IAIA44,151−5%

14Muscatine County, IAIA42,745+2%

15Marshall County, IAIA40,648+3%

16Des Moines County, IAIA40,325−5%

17Webster County, IAIA38,013−6%

18Jasper County, IAIA36,842−1%

19Lee County, IAIA35,862−6%

20Wapello County, IAIA35,625−1%

21Sioux County, IAIA33,704+7%

22Marion County, IAIA33,309+4%

23Boone County, IAIA26,306+0%

24Benton County, IAIA26,076+3%

25Plymouth County, IAIA24,986+1%

26Bremer County, IAIA24,276+4%

27Mahaska County, IAIA22,381+0%

28Washington County, IAIA21,704+5%

29Winneshiek County, IAIA21,056−1%

30Buchanan County, IAIA20,958−1%

31Fayette County, IAIA20,880−5%

32Carroll County, IAIA20,816−3%

33Jones County, IAIA20,638+2%

34Buena Vista County, IAIA20,260−1%

35Henry County, IAIA20,145−1%

36Jackson County, IAIA19,848−2%

37Poweshiek County, IAIA18,914+1%

38Cedar County, IAIA18,499+2%

39Clayton County, IAIA18,129−3%

40Tama County, IAIA17,767−2%

41Delaware County, IAIA17,764−3%

42Hardin County, IAIA17,534−7%

43Crawford County, IAIA17,096+1%

44Jefferson County, IAIA16,843+4%

45Clay County, IAIA16,667−4%

46Dickinson County, IAIA16,667+1%

47Iowa County, IAIA16,355+4%

48Floyd County, IAIA16,303−4%

49Page County, IAIA15,932−6%

50Madison County, IAIA15,679+12%

51Hamilton County, IAIA15,673−5%

52Kossuth County, IAIA15,543−9%

53Mills County, IAIA15,059+4%

54Harrison County, IAIA14,928−5%

55Butler County, IAIA14,867−3%

56O'Brien County, IAIA14,398−5%

57Allamakee County, IAIA14,330−2%

58Cass County, IAIA13,956−5%

59Wright County, IAIA13,229−8%

60Appanoose County, IAIA12,887−6%

61Union County, IAIA12,534+2%

62Grundy County, IAIA12,453+1%

63Chickasaw County, IAIA12,439−5%

64Shelby County, IAIA12,167−8%

65Cherokee County, IAIA12,072−7%

66Lyon County, IAIA11,581−2%

67Louisa County, IAIA11,387−7%

68Hancock County, IAIA11,341−6%

69Guthrie County, IAIA10,954−4%

70Winnebago County, IAIA10,866−7%

71Mitchell County, IAIA10,776−1%

72Montgomery County, IAIA10,740−9%

73Franklin County, IAIA10,680−0%

74Keokuk County, IAIA10,511−8%

75Sac County, IAIA10,350−10%

76Emmet County, IAIA10,302−7%

77Humboldt County, IAIA9,815−5%

78Calhoun County, IAIA9,670−13%

79Howard County, IAIA9,566−4%

80Palo Alto County, IAIA9,421−7%

81Greene County, IAIA9,336−10%

82Clarke County, IAIA9,286+2%

83Monona County, IAIA9,243−8%

84Lucas County, IAIA8,898−6%

85Davis County, IAIA8,753+2%

86Decatur County, IAIA8,457−3%

87Monroe County, IAIA7,970−1%

88Adair County, IAIA7,682−7%

89Worth County, IAIA7,598−4%

90Van Buren County, IAIA7,570−3%

91Fremont County, IAIA7,441−7%

92Pocahontas County, IAIA7,310−16%

93Ida County, IAIA7,089−10%

94Osceola County, IAIA6,462−8%

95Wayne County, IAIA6,403−5%

96Taylor County, IAIA6,317−9%

97Audubon County, IAIA6,119−10%

98Ringgold County, IAIA5,131−6%

99Adams County, IAIA4,029−10%

SHOWING 1–99 OF 99

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UPDATED 2026-07-15 · DATA: US CENSUS BUREAU DECENNIAL CENSUS