RANKING · 2000 CENSUS · 99 SHOWN OF 99

Largest by population, Iowa counties · 2000

The most populous Iowa counties as of the 2000 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 1990

01Polk County, IAIA374,601+15%

02Linn County, IAIA191,701+14%

03Scott County, IAIA158,668+5%

04Black Hawk County, IAIA128,012+3%

05Johnson County, IAIA111,006+15%

06Woodbury County, IAIA103,877+6%

07Dubuque County, IAIA89,143+3%

08Pottawattamie County, IAIA87,704+6%

09Story County, IAIA79,981+8%

10Clinton County, IAIA50,149−2%

11Cerro Gordo County, IAIA46,447−1%

12Des Moines County, IAIA42,351−1%

13Muscatine County, IAIA41,722+5%

14Dallas County, IAIA40,750+37%

15Warren County, IAIA40,671+13%

16Webster County, IAIA40,235−0%

17Marshall County, IAIA39,311+3%

18Lee County, IAIA38,052−2%

19Jasper County, IAIA37,213+7%

20Wapello County, IAIA36,051+1%

21Marion County, IAIA32,052+7%

22Sioux County, IAIA31,589+6%

23Boone County, IAIA26,224+4%

24Benton County, IAIA25,308+13%

25Plymouth County, IAIA24,849+6%

26Bremer County, IAIA23,325+2%

27Mahaska County, IAIA22,335+4%

28Fayette County, IAIA22,008+1%

29Carroll County, IAIA21,421−0%

30Winneshiek County, IAIA21,310+2%

31Buchanan County, IAIA21,093+1%

32Washington County, IAIA20,670+5%

33Buena Vista County, IAIA20,411+2%

34Henry County, IAIA20,336+6%

35Jackson County, IAIA20,296+2%

36Jones County, IAIA20,221+4%

37Poweshiek County, IAIA18,815−1%

38Hardin County, IAIA18,812−1%

39Clayton County, IAIA18,678−2%

40Delaware County, IAIA18,404+2%

41Cedar County, IAIA18,187+5%

42Tama County, IAIA18,103+4%

43Clay County, IAIA17,372−1%

44Kossuth County, IAIA17,163−8%

45Page County, IAIA16,976+1%

46Crawford County, IAIA16,942+1%

47Floyd County, IAIA16,900−1%

48Hamilton County, IAIA16,438+2%

49Dickinson County, IAIA16,424+10%

50Jefferson County, IAIA16,181−1%

51Iowa County, IAIA15,671+7%

52Harrison County, IAIA15,666+6%

53Butler County, IAIA15,305−3%

54O'Brien County, IAIA15,102−2%

55Cass County, IAIA14,684−3%

56Allamakee County, IAIA14,675+6%

57Mills County, IAIA14,547+10%

58Wright County, IAIA14,334+0%

59Madison County, IAIA14,019+12%

60Appanoose County, IAIA13,721−0%

61Shelby County, IAIA13,173−0%

62Chickasaw County, IAIA13,095−2%

63Cherokee County, IAIA13,035−8%

64Grundy County, IAIA12,369+3%

65Union County, IAIA12,309−3%

66Louisa County, IAIA12,183+5%

67Hancock County, IAIA12,100−4%

68Montgomery County, IAIA11,771−3%

69Lyon County, IAIA11,763−2%

70Winnebago County, IAIA11,723−3%

71Sac County, IAIA11,529−6%

72Keokuk County, IAIA11,400−2%

73Guthrie County, IAIA11,353+4%

74Calhoun County, IAIA11,115−3%

75Emmet County, IAIA11,027−5%

76Mitchell County, IAIA10,874−0%

77Franklin County, IAIA10,704−6%

78Humboldt County, IAIA10,381−3%

79Greene County, IAIA10,366+3%

80Palo Alto County, IAIA10,147−5%

81Monona County, IAIA10,020−0%

82Howard County, IAIA9,932+1%

83Lucas County, IAIA9,422+4%

84Clarke County, IAIA9,133+10%

85Decatur County, IAIA8,689+4%

86Pocahontas County, IAIA8,662−9%

87Davis County, IAIA8,541+3%

88Adair County, IAIA8,243−2%

89Monroe County, IAIA8,016−1%

90Fremont County, IAIA8,010−3%

91Worth County, IAIA7,909−1%

92Ida County, IAIA7,837−6%

93Van Buren County, IAIA7,809+2%

94Osceola County, IAIA7,003−4%

95Taylor County, IAIA6,958−2%

96Audubon County, IAIA6,830−7%

97Wayne County, IAIA6,730−5%

98Ringgold County, IAIA5,469+1%

99Adams County, IAIA4,482−8%

SHOWING 1–99 OF 99

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