RANKING · 2025 ESTIMATES · 99 SHOWN OF 99

Most population gained, Iowa counties

Iowa counties that added the most residents from the 2020 census to 2025, by raw count of people rather than percentage. This list covers the 99 counties in Iowa that qualify, ranked against each other statewide.

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SAME RANKING BYCities States Metros

YEAR2000 2010 2020 2025

RANKPLACESTATEPOPPOPULATION CHANGEVS 2000

01Polk County, IAIA516,546+24,145−49%

02Dallas County, IAIA118,457+18,779+71%

03Johnson County, IAIA160,044+7,190−52%

04Warren County, IAIA57,331+4,928+6%

05Story County, IAIA101,291+2,754−52%

06Linn County, IAIA232,028+1,729−92%

07Sioux County, IAIA36,774+902−47%

08Marion County, IAIA34,192+778−62%

09Madison County, IAIA17,270+722−53%

10Woodbury County, IAIA106,649+708−87%

11Jones County, IAIA21,253+607−22%

12Scott County, IAIA175,259+590−92%

13Benton County, IAIA26,004+429−85%

14Lyon County, IAIA12,354+420−322%

15Black Hawk County, IAIA131,532+388−91%

16Dickinson County, IAIA18,077+374−75%

17Jasper County, IAIA38,153+340−86%

18Buchanan County, IAIA20,883+318+28%

19Mills County, IAIA14,793+309−77%

20Bremer County, IAIA25,296+308−40%

21Wayne County, IAIA6,738+241−172%

22Lucas County, IAIA8,847+213−39%

23Delaware County, IAIA17,674+186−50%

24Allamakee County, IAIA14,238+177−78%

25Guthrie County, IAIA10,782+159−62%

26Davis County, IAIA9,230+120−48%

27Dubuque County, IAIA99,381+115−96%

28Washington County, IAIA22,667+102−90%

29Mitchell County, IAIA10,650+85−257%

30Boone County, IAIA26,799+84−92%

31Harrison County, IAIA14,623+41−96%

32O'Brien County, IAIA14,220+38−111%

33Grundy County, IAIA12,361+32−91%

34Decatur County, IAIA7,655+10−97%

35Plymouth County, IAIA25,697-1−100%

36Ringgold County, IAIA4,642-21−143%

37Howard County, IAIA9,415-54−144%

38Shelby County, IAIA11,689-57+0%

39Taylor County, IAIA5,835-61−61%

40Van Buren County, IAIA7,131-72−154%

41Fremont County, IAIA6,522-83−62%

42Adams County, IAIA3,617-87−77%

43Adair County, IAIA7,403-93−44%

44Hamilton County, IAIA14,944-95−126%

45Palo Alto County, IAIA8,899-97−81%

46Worth County, IAIA7,338-105+28%

47Greene County, IAIA8,658-113−135%

48Wright County, IAIA12,801-142−318%

49Cedar County, IAIA18,359-146−118%

50Franklin County, IAIA9,868-151−77%

51Iowa County, IAIA16,504-158−115%

52Webster County, IAIA36,838-161+50%

53Audubon County, IAIA5,509-165−67%

54Cass County, IAIA12,960-167−62%

55Monroe County, IAIA7,406-171+74%

56Clarke County, IAIA9,574-174−121%

57Clay County, IAIA16,202-182−15%

58Humboldt County, IAIA9,409-188−50%

59Jackson County, IAIA19,288-197−157%

60Clayton County, IAIA16,845-198−47%

61Monona County, IAIA8,539-212+1414%

62Osceola County, IAIA5,980-212−20%

63Marshall County, IAIA39,890-215−121%

64Wapello County, IAIA35,210-227−162%

65Ida County, IAIA6,777-228−57%

66Keokuk County, IAIA9,797-236+5%

67Appanoose County, IAIA12,077-240+991%

68Pocahontas County, IAIA6,819-259−70%

69Hancock County, IAIA10,528-267−50%

70Emmet County, IAIA9,107-281−48%

71Butler County, IAIA14,049-285−33%

72Crawford County, IAIA16,237-288−272%

73Cherokee County, IAIA11,369-289−73%

74Sac County, IAIA9,525-289−64%

75Poweshiek County, IAIA18,368-294+35%

76Union County, IAIA11,829-309−30%

77Mahaska County, IAIA21,880-310−138%

78Montgomery County, IAIA10,002-328+8%

79Winneshiek County, IAIA19,733-337−173%

80Tama County, IAIA16,796-339−150%

81Chickasaw County, IAIA11,663-349+75%

82Page County, IAIA14,856-355−435%

83Calhoun County, IAIA9,562-365−7%

84Jefferson County, IAIA15,291-372+188%

85Buena Vista County, IAIA20,449-374−184%

86Louisa County, IAIA10,416-421−171%

87Hardin County, IAIA16,455-423+50%

88Winnebago County, IAIA10,251-428+7%

89Carroll County, IAIA20,303-457+22750%

90Clinton County, IAIA46,002-458−49%

91Fayette County, IAIA19,047-462−380%

92Kossuth County, IAIA14,322-506−65%

93Pottawattamie County, IAIA92,996-671−113%

94Floyd County, IAIA14,901-726+359%

95Cerro Gordo County, IAIA42,372-755+164%

96Des Moines County, IAIA38,077-833+217%

97Henry County, IAIA19,349-1,133−202%

98Lee County, IAIA32,306-1,249+97%

99Muscatine County, IAIA41,853-1,382−176%

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