Illinois Counties by Population (2025)

by Kristen Carney Kristen Carney

Updated: August 7, 2025

The most populous counties in Illinois are Cook County with 5,182,617, DuPage County at 937,142, Lake County with 718,604, Will County at 708,583, and Kane County with 520,997. You can get the most current Census population data for all 102 Illinois counties, sorted from the most populous counties in Illinois to the least, according to the 2024 Population Estimates Program.

Sure, you can copy this list right into your favorite spreadsheet tool. Or save yourself formatting headaches and grab the latest Illinois counties population data as a ready-to-use Excel™ file below. It's time to stop searching and start digging into data!

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Rank County Population
1 Cook County 5,182,617
2 DuPage County 937,142
3 Lake County 718,604
4 Will County 708,583
5 Kane County 520,997
6 McHenry County 315,959
7 Winnebago County 283,790
8 Madison County 263,017
9 St. Clair County 251,149
10 Champaign County 212,374
11 Sangamon County 194,345
12 Peoria County 179,630
13 McLean County 172,069
14 Kendall County 143,171
15 Rock Island County 142,731
16 Tazewell County 129,821
17 LaSalle County 108,390
18 Kankakee County 106,410
19 DeKalb County 101,335
20 Macon County 100,737
21 Vermilion County 71,106
22 Williamson County 67,064
23 Adams County 64,109
24 Whiteside County 54,657
25 Grundy County 53,835
26 Boone County 53,313
27 Jackson County 53,199
28 Ogle County 51,345
29 Knox County 48,716
30 Henry County 48,177
31 Coles County 46,423
32 Macoupin County 43,895
33 Stephenson County 43,088
34 Woodford County 38,290
35 Clinton County 37,087
36 Franklin County 37,033
37 Marion County 36,437
38 Jefferson County 36,107
39 Livingston County 35,375
40 Monroe County 34,969
41 Effingham County 34,602
42 Lee County 33,544
43 Christian County 33,247
44 Morgan County 32,618
45 Fulton County 32,510
46 Bureau County 32,486
47 Randolph County 29,903
48 Montgomery County 27,615
49 Logan County 27,518
50 McDonough County 26,662
51 Iroquois County 26,067
52 Saline County 22,826
53 Jo Daviess County 21,528
54 Fayette County 21,157
55 Jersey County 21,150
56 Shelby County 20,542
57 Perry County 20,272
58 Douglas County 19,824
59 Crawford County 18,388
60 Hancock County 17,008
61 Union County 16,886
62 Piatt County 16,628
63 Bond County 16,576
64 Edgar County 16,398
65 Warren County 16,217
66 Wayne County 15,928
67 Carroll County 15,444
68 Richland County 15,362
69 De Witt County 15,319
70 Mercer County 15,292
71 Clark County 15,076
72 Lawrence County 14,801
73 Moultrie County 14,365
74 Pike County 14,258
75 Massac County 13,627
76 Washington County 13,535
77 Ford County 13,451
78 White County 13,395
79 Johnson County 13,320
80 Clay County 12,821
81 Cass County 12,713
82 Mason County 12,543
83 Menard County 11,963
84 Marshall County 11,552
85 Greene County 11,417
86 Wabash County 10,979
87 Cumberland County 10,305
88 Jasper County 9,092
89 Hamilton County 7,818
90 Schuyler County 6,750
91 Brown County 6,307
92 Henderson County 6,048
93 Edwards County 5,984
94 Putnam County 5,633
95 Stark County 5,272
96 Scott County 4,880
97 Pulaski County 4,879
98 Gallatin County 4,690
99 Alexander County 4,594
100 Calhoun County 4,224
101 Pope County 3,703
102 Hardin County 3,550

United States Census Bureau. Annual Estimates of the Resident Population: April 1, 2020 to July 1, 2024. Population Division. May 2025.

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