RANKING · 2020 CENSUS · 99 SHOWN OF 99

Most population gained, Iowa counties · 2020

Iowa counties that added the most residents from the 2010 census to 2020, 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+61,761+30%

02Dallas County, IAIA118,457+33,543+205%

03Johnson County, IAIA160,044+21,972+48%

04Linn County, IAIA232,028+19,073−17%

05Scott County, IAIA175,259+9,445+23%

06Story County, IAIA101,291+8,995+57%

07Warren County, IAIA57,331+6,178+33%

08Dubuque County, IAIA99,381+5,613+105%

09Woodbury County, IAIA106,649+3,769−33%

10Sioux County, IAIA36,774+2,168+29%

11Dickinson County, IAIA18,077+1,036−32%

12Jasper County, IAIA38,153+971−60%

13Madison County, IAIA17,270+869−43%

14Washington County, IAIA22,667+861−19%

15Bremer County, IAIA25,296+712+39%

16Plymouth County, IAIA25,697+712−51%

17Buena Vista County, IAIA20,449+563+26%

18Pottawattamie County, IAIA92,996+509−90%

19Muscatine County, IAIA41,853+490−73%

20Clarke County, IAIA9,574+462−45%

21Boone County, IAIA26,799+409−61%

22Davis County, IAIA9,230+357+56%

23Lyon County, IAIA12,354+353−287%

24Henry County, IAIA19,349+337−70%

25Iowa County, IAIA16,504+307−71%

26Calhoun County, IAIA9,562+257−165%

27Marion County, IAIA34,192+105−95%

28Wayne County, IAIA6,738+94−128%

29Black Hawk County, IAIA131,532+54−99%

30Jones County, IAIA21,253+8−99%

31Cedar County, IAIA18,359+6−99%

32Carroll County, IAIA20,303-56+2700%

33Ida County, IAIA6,777-84−84%

34Howard County, IAIA9,415-97−179%

35Grundy County, IAIA12,361-124−136%

36Worth County, IAIA7,338-155+89%

37Adair County, IAIA7,403-186+12%

38Winnebago County, IAIA10,251-187−53%

39Wapello County, IAIA35,210-188−152%

40Mahaska County, IAIA21,880-191−123%

41Mitchell County, IAIA10,650-211+291%

42O'Brien County, IAIA14,220-216−37%

43Humboldt County, IAIA9,409-218−42%

44Pocahontas County, IAIA6,819-232−73%

45Poweshiek County, IAIA18,368-252+16%

46Lucas County, IAIA8,847-264−175%

47Allamakee County, IAIA14,238-269−133%

48Osceola County, IAIA5,980-270+2%

49Delaware County, IAIA17,674-276−175%

50Clay County, IAIA16,202-283+33%

51Wright County, IAIA12,801-286−540%

52Adams County, IAIA3,617-325−15%

53Guthrie County, IAIA10,782-331−179%

54Harrison County, IAIA14,623-346−137%

55Jackson County, IAIA19,288-363−205%

56Van Buren County, IAIA7,131-367−376%

57Buchanan County, IAIA20,883-393−258%

58Monroe County, IAIA7,406-393+301%

59Union County, IAIA11,829-396−10%

60Montgomery County, IAIA10,002-410+34%

61Cherokee County, IAIA11,369-414−61%

62Taylor County, IAIA5,835-421+170%

63Shelby County, IAIA11,689-421+639%

64Palo Alto County, IAIA8,899-425−19%

65Chickasaw County, IAIA11,663-427+114%

66Audubon County, IAIA5,509-445−12%

67Ringgold County, IAIA4,642-468−1055%

68Keokuk County, IAIA9,797-478+113%

69Monona County, IAIA8,539-492+3414%

70Benton County, IAIA26,004-501−117%

71Butler County, IAIA14,049-533+25%

72Sac County, IAIA9,525-536−33%

73Marshall County, IAIA39,890-543−152%

74Hancock County, IAIA10,528-546+1%

75Louisa County, IAIA10,416-550−193%

76Greene County, IAIA8,658-565−276%

77Appanoose County, IAIA12,077-570+2491%

78Crawford County, IAIA16,237-571−442%

79Mills County, IAIA14,793-575−143%

80Tama County, IAIA16,796-632−192%

81Hamilton County, IAIA14,944-634−273%

82Hardin County, IAIA16,455-656+133%

83Franklin County, IAIA9,868-661+0%

84Floyd County, IAIA14,901-676+328%

85Kossuth County, IAIA14,322-715−50%

86Page County, IAIA14,856-721−780%

87Decatur County, IAIA7,655-812−331%

88Cass County, IAIA12,960-829+87%

89Fremont County, IAIA6,522-836+287%

90Emmet County, IAIA9,107-914+69%

91Winneshiek County, IAIA19,733-986−313%

92Webster County, IAIA36,838-1,014+848%

93Cerro Gordo County, IAIA42,372-1,024+258%

94Clayton County, IAIA16,845-1,086+189%

95Jefferson County, IAIA15,291-1,180+815%

96Fayette County, IAIA19,047-1,371−931%

97Des Moines County, IAIA38,077-1,415+438%

98Lee County, IAIA32,306-2,307+263%

99Clinton County, IAIA46,002-2,656+198%

SHOWING 1–99 OF 99

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