RANKING · 2025 ESTIMATES · 102 SHOWN OF 102

Largest by population, Illinois counties

The most populous Illinois counties as of the 2025 population estimates. This list covers the 102 counties in Illinois that qualify, ranked against each other statewide. The median across all 102 is 25,916.

IllinoisAll states All rankings

SAME RANKING BYCities States Metros ZIP codes

YEAR1990 2000 2010 2020 2025

RANKPLACESTATETOTAL POPULATIONVS 2000

01Cook County, ILIL5,194,625−3%

02DuPage County, ILIL934,298+3%

03Lake County, ILIL719,339+12%

04Will County, ILIL712,253+42%

05Kane County, ILIL525,757+30%

06McHenry County, ILIL317,751+22%

07Winnebago County, ILIL283,674+2%

08Madison County, ILIL263,110+2%

09St. Clair County, ILIL250,708−2%

10Champaign County, ILIL209,972+17%

11Sangamon County, ILIL194,170+3%

12Peoria County, ILIL178,553−3%

13McLean County, ILIL171,419+14%

14▲1Kendall County, ILIL145,470+167%

15▼1Rock Island County, ILIL141,869−5%

16Tazewell County, ILIL130,049+1%

17LaSalle County, ILIL107,773−3%

18Kankakee County, ILIL105,525+2%

19▲1DeKalb County, ILIL101,835+14%

20▼1Macon County, ILIL99,300−13%

21Vermilion County, ILIL71,259−15%

22Williamson County, ILIL67,225+10%

23Adams County, ILIL64,267−6%

24Whiteside County, ILIL54,121−11%

25▲2Grundy County, ILIL54,052+44%

26▼1Boone County, ILIL53,568+28%

27▼1Jackson County, ILIL52,501−12%

28Ogle County, ILIL51,399+1%

29▲1Henry County, ILIL48,095−6%

30▼1Knox County, ILIL47,767−14%

31Coles County, ILIL46,607−12%

32Macoupin County, ILIL43,748−11%

33Stephenson County, ILIL43,220−12%

34Woodford County, ILIL38,111+7%

35▲3Clinton County, ILIL37,128+4%

36▼1Franklin County, ILIL36,916−5%

37▼1Marion County, ILIL36,382−13%

38▼1Jefferson County, ILIL36,147−10%

39Livingston County, ILIL35,057−12%

40Monroe County, ILIL34,840+26%

41Effingham County, ILIL34,519+1%

42▲1Christian County, ILIL33,443−5%

43▼1Lee County, ILIL32,914−9%

44Fulton County, ILIL32,901−14%

45▲1Morgan County, ILIL32,515−11%

46▼1Bureau County, ILIL32,510−8%

47Randolph County, ILIL29,921−12%

48Montgomery County, ILIL28,076−8%

49Logan County, ILIL27,182−13%

50▲1Iroquois County, ILIL26,150−17%

51▼1McDonough County, ILIL25,916−21%

52Saline County, ILIL22,772−15%

53Jo Daviess County, ILIL21,594−3%

54Jersey County, ILIL21,160−2%

55Fayette County, ILIL20,790−5%

56Shelby County, ILIL20,576−10%

57Perry County, ILIL20,160−13%

58Douglas County, ILIL19,8800%

59Crawford County, ILIL18,648−9%

60▲4Bond County, ILIL16,959−4%

61▼1Hancock County, ILIL16,803−16%

62▲3Piatt County, ILIL16,791+3%

63▼2Union County, ILIL16,656−9%

64▼2Edgar County, ILIL16,323−17%

65▼2Warren County, ILIL16,222−13%

66Wayne County, ILIL15,882−7%

67▲1Carroll County, ILIL15,419−8%

68▲1Mercer County, ILIL15,229−10%

69▼2Richland County, ILIL15,219−6%

70De Witt County, ILIL15,118−10%

71Clark County, ILIL15,114−11%

72▲2Moultrie County, ILIL14,371+1%

73Pike County, ILIL14,231−18%

74▼2Lawrence County, ILIL13,790−11%

75▲2Washington County, ILIL13,564−10%

76▼1Massac County, ILIL13,502−11%

77▲2Johnson County, ILIL13,363+4%

78▼2White County, ILIL13,250−14%

79▼1Ford County, ILIL13,216−7%

80Clay County, ILIL12,793−12%

81▲1Cass County, ILIL12,463−9%

82▼1Mason County, ILIL12,411−23%

83Menard County, ILIL11,863−5%

84▲1Marshall County, ILIL11,473−13%

85▼1Greene County, ILIL11,313−23%

86Wabash County, ILIL10,907−16%

87Cumberland County, ILIL10,208−9%

88Jasper County, ILIL9,032−11%

89Hamilton County, ILIL7,859−9%

90Schuyler County, ILIL6,657−7%

91▲2Brown County, ILIL6,401−8%

92▼1Henderson County, ILIL5,984−27%

93▼1Edwards County, ILIL5,898−15%

94Putnam County, ILIL5,619−8%

95Stark County, ILIL5,319−16%

96▲2Scott County, ILIL4,866−12%

97Pulaski County, ILIL4,820−34%

98▲1Gallatin County, ILIL4,616−28%

99▼3Alexander County, ILIL4,570−52%

100Calhoun County, ILIL4,300−15%

101Pope County, ILIL3,672−17%

102Hardin County, ILIL3,588−25%

SHOWING 1–102 OF 102

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