RANKING · 2025 ESTIMATES · 102 SHOWN OF 102

Most densely populated, Illinois counties

Illinois counties ranked by residents per square mile (2025). This list covers the 102 counties in Illinois that qualify, ranked against each other statewide. The median across all 102 is 45. Biggest climber in the top 100 since 2020: Piatt County, IL, up 5 places to #60.

Flip the list · Most sparsely populated, US counties →

IllinoisAll states All rankings

SAME RANKING BYCities States Metros

RELATEDLargest by population Fastest growing Fastest shrinking Most population gained Most population lost Most sparsely populated

YEAR1990 2000 2010 2020 2025

RANKPLACESTATEPOPPOPULATION DENSITYVS 2000

01Cook County, ILIL5,194,6255,497−3%

02DuPage County, ILIL934,2982,850+3%

03Lake County, ILIL719,3391,622+12%

04Kane County, ILIL525,7571,012+30%

05Will County, ILIL712,253852+42%

06Winnebago County, ILIL283,674553+2%

07McHenry County, ILIL317,751527+22%

08Kendall County, ILIL145,470454+167%

09St. Clair County, ILIL250,708381−2%

10Madison County, ILIL263,110368+2%

11Rock Island County, ILIL141,869332−5%

12Peoria County, ILIL178,553289−3%

13Sangamon County, ILIL194,170224+3%

14Champaign County, ILIL209,972211+17%

15Tazewell County, ILIL130,049201+1%

16Boone County, ILIL53,568191+28%

17Macon County, ILIL99,300171−13%

18▲1DeKalb County, ILIL101,835161+14%

19▼1Williamson County, ILIL67,225160+10%

20Kankakee County, ILIL105,525156+2%

21McLean County, ILIL171,419145+14%

22Grundy County, ILIL54,052129+44%

23LaSalle County, ILIL107,77395−3%

24▲1Coles County, ILIL46,60792−12%

25▲2Monroe County, ILIL34,84090+26%

26▼2Franklin County, ILIL36,91690−5%

27▼1Jackson County, ILIL52,50190−12%

28Vermilion County, ILIL71,25979−15%

29Whiteside County, ILIL54,12179−11%

30▲1Clinton County, ILIL37,12878+4%

31▼1Stephenson County, ILIL43,22077−12%

32Adams County, ILIL64,26775−6%

33Woodford County, ILIL38,11172+7%

34Effingham County, ILIL34,51972+1%

35▲1Ogle County, ILIL51,39968+1%

36▼1Knox County, ILIL47,76767−14%

37Marion County, ILIL36,38264−13%

38Jefferson County, ILIL36,14763−10%

39Saline County, ILIL22,77260−15%

40Henry County, ILIL48,09558−6%

41▲1Jersey County, ILIL21,16057−2%

42▲1Morgan County, ILIL32,51557−11%

43▼2Massac County, ILIL13,50257−11%

44Randolph County, ILIL29,92152−12%

45Macoupin County, ILIL43,74851−11%

46Wabash County, ILIL10,90749−16%

47▲2Douglas County, ILIL19,880480%

48▼1Christian County, ILIL33,44347−5%

49▼1Perry County, ILIL20,16046−13%

50Lee County, ILIL32,91445−9%

51▲2Bond County, ILIL16,95945−4%

52Logan County, ILIL27,18244−13%

53▼2McDonough County, ILIL25,91644−21%

54▲1Moultrie County, ILIL14,37143+1%

55▼1Richland County, ILIL15,21942−6%

56Crawford County, ILIL18,64842−9%

57Union County, ILIL16,65640−9%

58▲1Montgomery County, ILIL28,07640−8%

59▲4Johnson County, ILIL13,36339+4%

60▲5Piatt County, ILIL16,79138+3%

61De Witt County, ILIL15,11838−10%

62Fulton County, ILIL32,90138−14%

63▼3Menard County, ILIL11,86338−5%

64Bureau County, ILIL32,51037−8%

65▼7Lawrence County, ILIL13,79037−11%

66Jo Daviess County, ILIL21,59436−3%

67▲1Putnam County, ILIL5,61935−8%

68▼1Carroll County, ILIL15,41935−8%

69▲1Livingston County, ILIL35,05734−12%

70▼1Cass County, ILIL12,46333−9%

71▲1Clark County, ILIL15,11430−11%

72▼1Warren County, ILIL16,22230−13%

73Marshall County, ILIL11,47330−13%

74Cumberland County, ILIL10,20830−9%

75Fayette County, ILIL20,79029−5%

76Clay County, ILIL12,79327−12%

77▲3Ford County, ILIL13,21627−7%

78▲1Mercer County, ILIL15,22927−10%

79▲2Shelby County, ILIL20,57627−10%

80▼2White County, ILIL13,25027−14%

81▼4Edwards County, ILIL5,89827−15%

82Edgar County, ILIL16,32326−17%

83Pulaski County, ILIL4,82024−34%

84Washington County, ILIL13,56424−10%

85▲1Iroquois County, ILIL26,15023−17%

86▼1Mason County, ILIL12,41123−23%

87Wayne County, ILIL15,88222−7%

88▲1Hancock County, ILIL16,80321−16%

89▲3Brown County, ILIL6,40121−8%

90Greene County, ILIL11,31321−23%

91Hardin County, ILIL3,58820−25%

92▼4Alexander County, ILIL4,57019−52%

93Scott County, ILIL4,86619−12%

94▲1Stark County, ILIL5,31918−16%

95▼1Jasper County, ILIL9,03218−11%

96Hamilton County, ILIL7,85918−9%

97Pike County, ILIL14,23117−18%

98Calhoun County, ILIL4,30017−15%

99Henderson County, ILIL5,98416−27%

100Schuyler County, ILIL6,65715−7%

101Gallatin County, ILIL4,61614−28%

102Pope County, ILIL3,67210−17%

SHOWING 1–102 OF 102

Download CSV (full list, 102 rows)

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