RANKING · 1990 CENSUS · 102 SHOWN OF 102

Youngest by median age, Illinois counties · 1990

Illinois counties with the youngest median age (1990 ACS). This list covers the 102 counties in Illinois that qualify, ranked against each other statewide. The median across all 102 is 35.4.

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SAME RANKING BYCities States Metros ZIP codes

RELATEDLargest foreign-born population Most residents with a disability Largest veteran population Most uninsured people Largest senior population Most unmarried people

YEAR1990 2000 2010 2020 2024

RANKPLACESTATEPOPMEDIAN AGEVS –

01Jackson County, ILIL52,50126.5–

02DeKalb County, ILIL101,83527.3–

03McDonough County, ILIL25,91627.4–

04Champaign County, ILIL209,97227.8–

05McLean County, ILIL171,41929.1–

06Coles County, ILIL46,60729.9–

07Kane County, ILIL525,75730.9–

08Will County, ILIL712,25331.2–

09Lake County, ILIL719,33931.7–

10Effingham County, ILIL34,51931.9–

11Kendall County, ILIL145,47032.2–

12St. Clair County, ILIL250,70832.2–

13McHenry County, ILIL317,75132.4–

14DuPage County, ILIL934,29832.4–

15Cook County, ILIL5,194,62532.8–

16Clinton County, ILIL37,12832.9–

17Kankakee County, ILIL105,52532.9–

18Boone County, ILIL53,56833.2–

19Jersey County, ILIL21,16033.2–

20Grundy County, ILIL54,05233.3–

21Brown County, ILIL6,40133.5–

22Winnebago County, ILIL283,67433.5–

23Cumberland County, ILIL10,20833.8–

24Peoria County, ILIL178,55333.9–

25Ogle County, ILIL51,39934.0–

26Madison County, ILIL263,11034.0–

27Monroe County, ILIL34,84034.0–

28Randolph County, ILIL29,92134.0–

29Woodford County, ILIL38,11134.1–

30Livingston County, ILIL35,05734.3–

31Sangamon County, ILIL194,17034.3–

32Lee County, ILIL32,91434.3–

33Morgan County, ILIL32,51534.5–

34Douglas County, ILIL19,88034.5–

35Jasper County, ILIL9,03234.5–

36Logan County, ILIL27,18234.6–

37Alexander County, ILIL4,57034.7–

38Tazewell County, ILIL130,04934.8–

39Whiteside County, ILIL54,12134.8–

40Jefferson County, ILIL36,14734.9–

41Pulaski County, ILIL4,82034.9–

42Wabash County, ILIL10,90735.0–

43Rock Island County, ILIL141,86935.0–

44Stephenson County, ILIL43,22035.0–

45Macon County, ILIL99,30035.0–

46Bond County, ILIL16,95935.0–

47Marion County, ILIL36,38235.1–

48Warren County, ILIL16,22235.2–

49Fayette County, ILIL20,79035.3–

50Montgomery County, ILIL28,07635.3–

51De Witt County, ILIL15,11835.4–

52Perry County, ILIL20,16035.4–

53Menard County, ILIL11,86335.4–

54LaSalle County, ILIL107,77335.5–

55Vermilion County, ILIL71,25935.5–

56Johnson County, ILIL13,36335.5–

57Richland County, ILIL15,21935.6–

58Pope County, ILIL3,67235.6–

59Cass County, ILIL12,46335.8–

60Adams County, ILIL64,26735.8–

61Washington County, ILIL13,56435.9–

62Henry County, ILIL48,09535.9–

63Scott County, ILIL4,86635.9–

64Putnam County, ILIL5,61935.9–

65Macoupin County, ILIL43,74836.0–

66Greene County, ILIL11,31336.0–

67Piatt County, ILIL16,79136.1–

68Mercer County, ILIL15,22936.1–

69Williamson County, ILIL67,22536.1–

70Shelby County, ILIL20,57636.2–

71Jo Daviess County, ILIL21,59436.2–

72Bureau County, ILIL32,51036.2–

73Knox County, ILIL47,76736.3–

74Christian County, ILIL33,44336.4–

75Mason County, ILIL12,41136.5–

76Ford County, ILIL13,21636.6–

77Moultrie County, ILIL14,37136.7–

78Clay County, ILIL12,79336.8–

79Clark County, ILIL15,11436.9–

80Fulton County, ILIL32,90136.9–

81Crawford County, ILIL18,64837.0–

82Iroquois County, ILIL26,15037.1–

83Wayne County, ILIL15,88237.3–

84Hardin County, ILIL3,58837.3–

85Carroll County, ILIL15,41937.4–

86Hancock County, ILIL16,80337.4–

87Edwards County, ILIL5,89837.5–

88Edgar County, ILIL16,32337.5–

89Henderson County, ILIL5,98437.6–

90Marshall County, ILIL11,47337.6–

91Pike County, ILIL14,23137.7–

92Schuyler County, ILIL6,65737.7–

93Lawrence County, ILIL13,79037.8–

94Stark County, ILIL5,31937.8–

95Massac County, ILIL13,50237.9–

96Union County, ILIL16,65638.0–

97Franklin County, ILIL36,91638.0–

98Calhoun County, ILIL4,30038.3–

99White County, ILIL13,25038.3–

100Saline County, ILIL22,77238.3–

101Hamilton County, ILIL7,85939.5–

102Gallatin County, ILIL4,61640.0–

SHOWING 1–102 OF 102

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UPDATED 2026-09-11 · DATA: US CENSUS BUREAU DECENNIAL CENSUS