RANKING · 2025 ESTIMATES · 99 SHOWN OF 99

Largest by population, Iowa counties

The most populous Iowa counties as of the 2025 population estimates. This list covers the 99 counties in Iowa that qualify, ranked against each other statewide.

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 2000

01Polk County, IAIA516,546+38%

02Linn County, IAIA232,028+21%

03Scott County, IAIA175,259+10%

04Johnson County, IAIA160,044+44%

05Black Hawk County, IAIA131,532+3%

06Dallas County, IAIA118,457+191%

07Woodbury County, IAIA106,649+3%

08Story County, IAIA101,291+27%

09Dubuque County, IAIA99,381+11%

10Pottawattamie County, IAIA92,996+6%

11Warren County, IAIA57,331+41%

12Clinton County, IAIA46,002−8%

13Cerro Gordo County, IAIA42,372−9%

14Muscatine County, IAIA41,853+0%

15Marshall County, IAIA39,890+1%

16Jasper County, IAIA38,153+3%

17Des Moines County, IAIA38,077−10%

18Webster County, IAIA36,838−8%

19Sioux County, IAIA36,774+16%

20Wapello County, IAIA35,210−2%

21Marion County, IAIA34,192+7%

22Lee County, IAIA32,306−15%

23Boone County, IAIA26,799+2%

24Benton County, IAIA26,004+3%

25Plymouth County, IAIA25,697+3%

26Bremer County, IAIA25,296+8%

27Washington County, IAIA22,667+10%

28Mahaska County, IAIA21,880−2%

29Jones County, IAIA21,253+5%

30Buchanan County, IAIA20,883−1%

31Buena Vista County, IAIA20,449+0%

32Carroll County, IAIA20,303−5%

33Winneshiek County, IAIA19,733−7%

34Henry County, IAIA19,349−5%

35Jackson County, IAIA19,288−5%

36Fayette County, IAIA19,047−13%

37Poweshiek County, IAIA18,368−2%

38Cedar County, IAIA18,359+1%

39Dickinson County, IAIA18,077+10%

40Delaware County, IAIA17,674−4%

41Madison County, IAIA17,270+23%

42Clayton County, IAIA16,845−10%

43Tama County, IAIA16,796−7%

44Iowa County, IAIA16,504+5%

45Hardin County, IAIA16,455−13%

46Crawford County, IAIA16,237−4%

47Clay County, IAIA16,202−7%

48Jefferson County, IAIA15,291−6%

49Hamilton County, IAIA14,944−9%

50Floyd County, IAIA14,901−12%

51Page County, IAIA14,856−12%

52Mills County, IAIA14,793+2%

53Harrison County, IAIA14,623−7%

54Kossuth County, IAIA14,322−17%

55Allamakee County, IAIA14,238−3%

56O'Brien County, IAIA14,220−6%

57Butler County, IAIA14,049−8%

58Cass County, IAIA12,960−12%

59Wright County, IAIA12,801−11%

60Grundy County, IAIA12,361−0%

61Lyon County, IAIA12,354+5%

62Appanoose County, IAIA12,077−12%

63Union County, IAIA11,829−4%

64Shelby County, IAIA11,689−11%

65Chickasaw County, IAIA11,663−11%

66Cherokee County, IAIA11,369−13%

67Guthrie County, IAIA10,782−5%

68Mitchell County, IAIA10,650−2%

69Hancock County, IAIA10,528−13%

70Louisa County, IAIA10,416−15%

71Winnebago County, IAIA10,251−13%

72Montgomery County, IAIA10,002−15%

73Franklin County, IAIA9,868−8%

74Keokuk County, IAIA9,797−14%

75Clarke County, IAIA9,574+5%

76Calhoun County, IAIA9,562−14%

77Sac County, IAIA9,525−17%

78Howard County, IAIA9,415−5%

79Humboldt County, IAIA9,409−9%

80Davis County, IAIA9,230+8%

81Emmet County, IAIA9,107−17%

82Palo Alto County, IAIA8,899−12%

83Lucas County, IAIA8,847−6%

84Greene County, IAIA8,658−16%

85Monona County, IAIA8,539−15%

86Decatur County, IAIA7,655−12%

87Monroe County, IAIA7,406−8%

88Adair County, IAIA7,403−10%

89Worth County, IAIA7,338−7%

90Van Buren County, IAIA7,131−9%

91Pocahontas County, IAIA6,819−21%

92Ida County, IAIA6,777−14%

93Wayne County, IAIA6,738+0%

94Fremont County, IAIA6,522−19%

95Osceola County, IAIA5,980−15%

96Taylor County, IAIA5,835−16%

97Audubon County, IAIA5,509−19%

98Ringgold County, IAIA4,642−15%

99Adams County, IAIA3,617−19%

SHOWING 1–99 OF 99

Download CSV (full list, 99 rows)

UPDATED 2026-07-15 · DATA: US CENSUS BUREAU POPULATION ESTIMATES