RANKING · 2020 CENSUS · 102 SHOWN OF 102

Most densely populated, Illinois counties · 2020

Illinois counties ranked by residents per square mile (2023). This list covers the 102 counties in Illinois that qualify, ranked against each other statewide.

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SAME RANKING BYCities States Metros

RELATEDLargest by population Fastest growing Fastest shrinking Most sparsely populated Best broadband access Worst broadband access

YEAR1990 2000 2010 2020 2025

RANKPLACESTATEPOPPOPULATION DENSITYVS 2000

01Cook County, ILIL5,194,6255,583−2%

02DuPage County, ILIL934,2982,846+3%

03Lake County, ILIL719,3391,610+11%

04Kane County, ILIL525,757995+28%

05Will County, ILIL712,253833+39%

06Winnebago County, ILIL283,674556+2%

07McHenry County, ILIL317,751514+19%

08Kendall County, ILIL145,470412+142%

09St. Clair County, ILIL250,708391+1%

10Madison County, ILIL263,110372+3%

11Rock Island County, ILIL141,869338−3%

12Peoria County, ILIL178,553294−1%

13Sangamon County, ILIL194,170226+4%

14Champaign County, ILIL209,972207+15%

15Tazewell County, ILIL130,049203+2%

16Boone County, ILIL53,568190+28%

17Macon County, ILIL99,300179−9%

18Williamson County, ILIL67,225160+10%

19DeKalb County, ILIL101,835159+13%

20Kankakee County, ILIL105,525159+4%

21McLean County, ILIL171,419144+14%

22Grundy County, ILIL54,052126+40%

23LaSalle County, ILIL107,77397−2%

24Franklin County, ILIL36,91692−3%

25Coles County, ILIL46,60792−12%

26Jackson County, ILIL52,50191−11%

27Monroe County, ILIL34,84091+27%

28Vermilion County, ILIL71,25983−12%

29Whiteside County, ILIL54,12181−8%

30Stephenson County, ILIL43,22079−9%

31Clinton County, ILIL37,12878+4%

32Adams County, ILIL64,26777−4%

33Woodford County, ILIL38,11173+8%

34Effingham County, ILIL34,51972+1%

35Knox County, ILIL47,76770−11%

36Ogle County, ILIL51,39968+1%

37Marion County, ILIL36,38266−10%

38Jefferson County, ILIL36,14765−7%

39Saline County, ILIL22,77263−11%

40Henry County, ILIL48,09560−3%

41Massac County, ILIL13,50260−7%

42Jersey County, ILIL21,16058−1%

43Morgan County, ILIL32,51558−10%

44Randolph County, ILIL29,92152−11%

45Macoupin County, ILIL43,74852−8%

46Wabash County, ILIL10,90751−12%

47Christian County, ILIL33,44348−4%

48Perry County, ILIL20,16047−9%

49Douglas County, ILIL19,88047−1%

50Lee County, ILIL32,91447−5%

51McDonough County, ILIL25,91646−17%

52Logan County, ILIL27,18245−10%

53Bond County, ILIL16,95944−5%

54Richland County, ILIL15,21944−2%

55Moultrie County, ILIL14,37143+2%

56Crawford County, ILIL18,64842−9%

57Union County, ILIL16,65642−6%

58Lawrence County, ILIL13,79041−1%

59Montgomery County, ILIL28,07640−8%

60Menard County, ILIL11,86339−2%

61De Witt County, ILIL15,11839−8%

62Fulton County, ILIL32,90139−12%

63Johnson County, ILIL13,36339+3%

64Bureau County, ILIL32,51038−6%

65Piatt County, ILIL16,79138+2%

66Jo Daviess County, ILIL21,59437−1%

67Carroll County, ILIL15,41935−6%

68Putnam County, ILIL5,61935−7%

69Cass County, ILIL12,46335−5%

70Livingston County, ILIL35,05734−10%

71Warren County, ILIL16,22231−10%

72Clark County, ILIL15,11431−9%

73Marshall County, ILIL11,47330−11%

74Cumberland County, ILIL10,20830−7%

75Fayette County, ILIL20,79030−1%

76Clay County, ILIL12,79328−9%

77Edwards County, ILIL5,89828−10%

78White County, ILIL13,25028−10%

79Mercer County, ILIL15,22928−7%

80Ford County, ILIL13,21628−5%

81Shelby County, ILIL20,57628−8%

82Edgar County, ILIL16,32327−14%

83Pulaski County, ILIL4,82026−29%

84Washington County, ILIL13,56424−9%

85Mason County, ILIL12,41124−18%

86Iroquois County, ILIL26,15024−14%

87Wayne County, ILIL15,88223−6%

88Alexander County, ILIL4,57022−45%

89Hancock County, ILIL16,80322−12%

90Greene County, ILIL11,31322−19%

91Hardin County, ILIL3,58821−24%

92Brown County, ILIL6,40120−10%

93Scott County, ILIL4,86620−11%

94Jasper County, ILIL9,03219−8%

95Stark County, ILIL5,31919−15%

96Hamilton County, ILIL7,85918−7%

97Pike County, ILIL14,23118−15%

98Calhoun County, ILIL4,30017−13%

99Henderson County, ILIL5,98417−22%

100Schuyler County, ILIL6,65716−4%

101Gallatin County, ILIL4,61615−23%

102Pope County, ILIL3,67210−15%

SHOWING 1–102 OF 102

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UPDATED 2026-06-02 · DATA: US CENSUS BUREAU ACS 5-YEAR ESTIMATES