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. The median across all 99 is -151. Biggest climber in the top 100 since 2020: Mills County, IA, up 60 places to #19.

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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%

04▲3Warren County, IAIA57,331+4,928+6%

05▲1Story County, IAIA101,291+2,754−52%

06▼2Linn County, IAIA232,028+1,729−92%

07▲3Sioux County, IAIA36,774+902−47%

08▲19Marion County, IAIA34,192+778−62%

09▲4Madison County, IAIA17,270+722−53%

10▼1Woodbury County, IAIA106,649+708−87%

11▲19Jones County, IAIA21,253+607−22%

12▼7Scott County, IAIA175,259+590−92%

13▲57Benton County, IAIA26,004+429−85%

14▲9Lyon County, IAIA12,354+420−322%

15▲14Black Hawk County, IAIA131,532+388−91%

16▼5Dickinson County, IAIA18,077+374−75%

17▼5Jasper County, IAIA38,153+340−86%

18▲39Buchanan County, IAIA20,883+318+28%

19▲60Mills County, IAIA14,793+309−77%

20▼5Bremer County, IAIA25,296+308−40%

21▲7Wayne County, IAIA6,738+241−172%

22▲24Lucas County, IAIA8,847+213−39%

23▲26Delaware County, IAIA17,674+186−50%

24▲23Allamakee County, IAIA14,238+177−78%

25▲28Guthrie County, IAIA10,782+159−62%

26▼4Davis County, IAIA9,230+120−48%

27▼19Dubuque County, IAIA99,381+115−96%

28▼14Washington County, IAIA22,667+102−90%

29▲12Mitchell County, IAIA10,650+85−257%

30▼9Boone County, IAIA26,799+84−92%

31▲23Harrison County, IAIA14,623+41−96%

32▲10O'Brien County, IAIA14,220+38−111%

33▲2Grundy County, IAIA12,361+32−91%

34▲53Decatur County, IAIA7,655+10−97%

35▼19Plymouth County, IAIA25,697-1−100%

36▲31Ringgold County, IAIA4,642-21−143%

37▼3Howard County, IAIA9,415-54−144%

38▲25Shelby County, IAIA11,689-570%

39▲23Taylor County, IAIA5,835-61−61%

40▲16Van Buren County, IAIA7,131-72−154%

41▲48Fremont County, IAIA6,522-83−62%

42▲10Adams County, IAIA3,617-87−77%

43▼6Adair County, IAIA7,403-93−44%

44▲37Hamilton County, IAIA14,944-95−126%

45▲19Palo Alto County, IAIA8,899-97−81%

46▼10Worth County, IAIA7,338-105+28%

47▲29Greene County, IAIA8,658-113−135%

48▲3Wright County, IAIA12,801-142−318%

49▼18Cedar County, IAIA18,359-146−118%

50▲33Franklin County, IAIA9,868-151−77%

51▼26Iowa County, IAIA16,504-158−115%

52▲40Webster County, IAIA36,838-161+50%

53▲13Audubon County, IAIA5,509-165−67%

54▲34Cass County, IAIA12,960-167−62%

55▲3Monroe County, IAIA7,406-171+74%

56▼36Clarke County, IAIA9,574-174−121%

57▼7Clay County, IAIA16,202-182−15%

58▼15Humboldt County, IAIA9,409-188−50%

59▼4Jackson County, IAIA19,288-197−157%

60▲34Clayton County, IAIA16,845-198−47%

61▲8Monona County, IAIA8,539-212+1414%

62▼14Osceola County, IAIA5,980-212−20%

63▲10Marshall County, IAIA39,890-215−121%

64▼25Wapello County, IAIA35,210-227−162%

65▼32Ida County, IAIA6,777-228−57%

66▲2Keokuk County, IAIA9,797-236+5%

67▲10Appanoose County, IAIA12,077-240+991%

68▼24Pocahontas County, IAIA6,819-259−70%

69▲5Hancock County, IAIA10,528-267−50%

70▲20Emmet County, IAIA9,107-281−48%

71Butler County, IAIA14,049-285−33%

72▲6Crawford County, IAIA16,237-288−272%

73▼12Cherokee County, IAIA11,369-289−73%

74▼2Sac County, IAIA9,525-289−64%

75▼30Poweshiek County, IAIA18,368-294+35%

76▼17Union County, IAIA11,829-309−30%

77▼37Mahaska County, IAIA21,880-310−138%

78▼18Montgomery County, IAIA10,002-328+8%

79▲12Winneshiek County, IAIA19,733-337−173%

80Tama County, IAIA16,796-339−150%

81▼16Chickasaw County, IAIA11,663-349+75%

82▲4Page County, IAIA14,856-355−435%

83▼57Calhoun County, IAIA9,562-365−7%

84▲11Jefferson County, IAIA15,291-372+188%

85▼68Buena Vista County, IAIA20,449-374−184%

86▼11Louisa County, IAIA10,416-421−171%

87▼5Hardin County, IAIA16,455-423+50%

88▼50Winnebago County, IAIA10,251-428+7%

89▼57Carroll County, IAIA20,303-457+22750%

90▲9Clinton County, IAIA46,002-458−49%

91▲5Fayette County, IAIA19,047-462−380%

92▼7Kossuth County, IAIA14,322-506−65%

93▼75Pottawattamie County, IAIA92,996-671−113%

94▼10Floyd County, IAIA14,901-726+359%

95▼2Cerro Gordo County, IAIA42,372-755+164%

96▲1Des Moines County, IAIA38,077-833+217%

97▼73Henry County, IAIA19,349-1,133−202%

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

99▼80Muscatine County, IAIA41,853-1,382−176%

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UPDATED 2026-09-11 · DATA: US CENSUS BUREAU POPULATION ESTIMATES