RANKING · 1990 CENSUS · 99 SHOWN OF 99

Largest by population, Iowa counties · 1990

The most populous Iowa counties as of the 1990 population estimates. This list covers the 99 counties in Iowa that qualify, ranked against each other statewide. The median across all 99 is 15,731.

IowaAll states All rankings

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 –

01Polk County, IAIA327,140–

02Linn County, IAIA168,767–

03Scott County, IAIA150,979–

04Black Hawk County, IAIA123,798–

05Woodbury County, IAIA98,276–

06Johnson County, IAIA96,119–

07Dubuque County, IAIA86,403–

08Pottawattamie County, IAIA82,628–

09Story County, IAIA74,252–

10Clinton County, IAIA51,040–

11Cerro Gordo County, IAIA46,733–

12Des Moines County, IAIA42,614–

13Webster County, IAIA40,342–

14Muscatine County, IAIA39,907–

15Lee County, IAIA38,687–

16Marshall County, IAIA38,276–

17Warren County, IAIA36,033–

18Wapello County, IAIA35,687–

19Jasper County, IAIA34,795–

20Marion County, IAIA30,001–

21Sioux County, IAIA29,903–

22Dallas County, IAIA29,755–

23Boone County, IAIA25,186–

24Plymouth County, IAIA23,388–

25Bremer County, IAIA22,813–

26Benton County, IAIA22,429–

27Fayette County, IAIA21,843–

28Mahaska County, IAIA21,522–

29Carroll County, IAIA21,423–

30Winneshiek County, IAIA20,847–

31Buchanan County, IAIA20,844–

32Buena Vista County, IAIA19,965–

33Jackson County, IAIA19,950–

34Washington County, IAIA19,612–

35Jones County, IAIA19,444–

36Henry County, IAIA19,226–

37Hardin County, IAIA19,094–

38Clayton County, IAIA19,054–

39Poweshiek County, IAIA19,033–

40Kossuth County, IAIA18,591–

41Delaware County, IAIA18,035–

42Clay County, IAIA17,585–

43Tama County, IAIA17,419–

44Cedar County, IAIA17,381–

45Floyd County, IAIA17,058–

46Page County, IAIA16,870–

47Crawford County, IAIA16,775–

48Jefferson County, IAIA16,310–

49Hamilton County, IAIA16,071–

50Butler County, IAIA15,731–

51O'Brien County, IAIA15,444–

52Cass County, IAIA15,128–

53Dickinson County, IAIA14,909–

54Harrison County, IAIA14,730–

55Iowa County, IAIA14,630–

56Wright County, IAIA14,269–

57Cherokee County, IAIA14,098–

58Allamakee County, IAIA13,855–

59Appanoose County, IAIA13,743–

60Chickasaw County, IAIA13,295–

61Shelby County, IAIA13,230–

62Mills County, IAIA13,202–

63Union County, IAIA12,750–

64Hancock County, IAIA12,638–

65Madison County, IAIA12,483–

66Sac County, IAIA12,324–

67Winnebago County, IAIA12,122–

68Montgomery County, IAIA12,076–

69Grundy County, IAIA12,029–

70Lyon County, IAIA11,952–

71Keokuk County, IAIA11,624–

72Louisa County, IAIA11,592–

73Emmet County, IAIA11,569–

74Calhoun County, IAIA11,508–

75Franklin County, IAIA11,364–

76Guthrie County, IAIA10,935–

77Mitchell County, IAIA10,928–

78Humboldt County, IAIA10,756–

79Palo Alto County, IAIA10,669–

80Greene County, IAIA10,045–

81Monona County, IAIA10,034–

82Howard County, IAIA9,809–

83Pocahontas County, IAIA9,525–

84Lucas County, IAIA9,070–

85Adair County, IAIA8,409–

86Ida County, IAIA8,365–

87Decatur County, IAIA8,338–

88Davis County, IAIA8,312–

89Clarke County, IAIA8,287–

90Fremont County, IAIA8,226–

91Monroe County, IAIA8,114–

92Worth County, IAIA7,991–

93Van Buren County, IAIA7,676–

94Audubon County, IAIA7,334–

95Osceola County, IAIA7,267–

96Taylor County, IAIA7,114–

97Wayne County, IAIA7,067–

98Ringgold County, IAIA5,420–

99Adams County, IAIA4,866–

SHOWING 1–99 OF 99

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