RANKING · 2020 CENSUS · 102 SHOWN OF 102

Largest by population, Illinois counties · 2020

The most populous Illinois counties as of the 2020 population estimates. This list covers the 102 counties in Illinois that qualify, ranked against each other statewide.

IllinoisAll 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

01Cook County, ILIL5,275,541−2%

02DuPage County, ILIL932,877+3%

03Lake County, ILIL714,342+11%

04Will County, ILIL696,355+39%

05Kane County, ILIL516,522+28%

06McHenry County, ILIL310,229+19%

07Winnebago County, ILIL285,350+2%

08Madison County, ILIL265,859+3%

09St. Clair County, ILIL257,400+1%

10Champaign County, ILIL205,865+15%

11Sangamon County, ILIL196,343+4%

12Peoria County, ILIL181,830−1%

13McLean County, ILIL170,954+14%

14Rock Island County, ILIL144,672−3%

15Kendall County, ILIL131,869+142%

16Tazewell County, ILIL131,343+2%

17LaSalle County, ILIL109,658−2%

18Kankakee County, ILIL107,502+4%

19Macon County, ILIL103,998−9%

20DeKalb County, ILIL100,420+13%

21Vermilion County, ILIL74,188−12%

22Williamson County, ILIL67,153+10%

23Adams County, ILIL65,737−4%

24Whiteside County, ILIL55,691−8%

25Boone County, ILIL53,448+28%

26Jackson County, ILIL52,974−11%

27Grundy County, ILIL52,533+40%

28Ogle County, ILIL51,788+1%

29Knox County, ILIL49,967−11%

30Henry County, ILIL49,284−3%

31Coles County, ILIL46,863−12%

32Macoupin County, ILIL44,967−8%

33Stephenson County, ILIL44,630−9%

34Woodford County, ILIL38,467+8%

35Franklin County, ILIL37,804−3%

36Marion County, ILIL37,729−10%

37Jefferson County, ILIL37,113−7%

38Clinton County, ILIL36,899+4%

39Livingston County, ILIL35,815−10%

40Monroe County, ILIL34,962+27%

41Effingham County, ILIL34,668+1%

42Lee County, ILIL34,145−5%

43Christian County, ILIL34,032−4%

44Fulton County, ILIL33,609−12%

45Bureau County, ILIL33,244−6%

46Morgan County, ILIL32,915−10%

47Randolph County, ILIL30,163−11%

48Montgomery County, ILIL28,288−8%

49Logan County, ILIL27,987−10%

50McDonough County, ILIL27,238−17%

51Iroquois County, ILIL27,077−14%

52Saline County, ILIL23,768−11%

53Jo Daviess County, ILIL22,035−1%

54Jersey County, ILIL21,512−1%

55Fayette County, ILIL21,488−1%

56Shelby County, ILIL20,990−8%

57Perry County, ILIL20,945−9%

58Douglas County, ILIL19,740−1%

59Crawford County, ILIL18,679−9%

60Hancock County, ILIL17,620−12%

61Union County, ILIL17,244−6%

62Edgar County, ILIL16,866−14%

63Warren County, ILIL16,835−10%

64Bond County, ILIL16,725−5%

65Piatt County, ILIL16,673+2%

66Wayne County, ILIL16,179−6%

67Richland County, ILIL15,813−2%

68Carroll County, ILIL15,702−6%

69Mercer County, ILIL15,699−7%

70De Witt County, ILIL15,516−8%

71Clark County, ILIL15,455−9%

72Lawrence County, ILIL15,280−1%

73Pike County, ILIL14,739−15%

74Moultrie County, ILIL14,526+2%

75Massac County, ILIL14,169−7%

76White County, ILIL13,877−10%

77Washington County, ILIL13,761−9%

78Ford County, ILIL13,534−5%

79Johnson County, ILIL13,308+3%

80Clay County, ILIL13,288−9%

81Mason County, ILIL13,086−18%

82Cass County, ILIL13,042−5%

83Menard County, ILIL12,297−2%

84Greene County, ILIL11,985−19%

85Marshall County, ILIL11,742−11%

86Wabash County, ILIL11,361−12%

87Cumberland County, ILIL10,450−7%

88Jasper County, ILIL9,287−8%

89Hamilton County, ILIL7,993−7%

90Schuyler County, ILIL6,902−4%

91Henderson County, ILIL6,387−22%

92Edwards County, ILIL6,245−10%

93Brown County, ILIL6,244−10%

94Putnam County, ILIL5,637−7%

95Stark County, ILIL5,400−15%

96Alexander County, ILIL5,240−45%

97Pulaski County, ILIL5,193−29%

98Scott County, ILIL4,949−11%

99Gallatin County, ILIL4,946−23%

100Calhoun County, ILIL4,437−13%

101Pope County, ILIL3,763−15%

102Hardin County, ILIL3,649−24%

SHOWING 1–102 OF 102

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