Illinois Population By County in 2010

Updated on January 29, 2024.

Based on the US Census Vintage data estimates, in 2010, the population of Illinois was 12,840,545. Among all Illinois counties, Cook[object Promise] had the highest population (5,198,977), followed by DuPage[object Promise] (917,996), and Lake[object Promise] (704,179). Hardin[object Promise] was the least populated county (4,316).

Hover over or click on the counties in the map below to see the populations. The data can also be found in a table below. You can use the table to sort, filter, and explore the data further.

You can see similar information for other states and by state for the United States.

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Illinois Population By County in 2010
Illinois Population By County in 2010
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County Population % of State Population
Adams 67158 0.52
Alexander 8205 0.06
Bond 17789 0.14
Boone 54094 0.42
Brown 6919 0.05
Bureau 34959 0.27
Calhoun 5093 0.04
Carroll 15395 0.12
Cass 13632 0.11
Champaign 201558 1.57
Christian 34767 0.27
Clark 16291 0.13
Clay 13822 0.11
Clinton 37833 0.30
Coles 53865 0.42
Cook 5198977 40.49
Crawford 19801 0.15
Cumberland 11053 0.09
DeKalb 105151 0.82
De Witt 16589 0.13
Douglas 19977 0.16
DuPage 917996 7.15
Edgar 18509 0.14
Edwards 6739 0.05
Effingham 34222 0.27
Fayette 22140 0.17
Ford 14076 0.11
Franklin 40035 0.31
Fulton 37076 0.29
Gallatin 5574 0.04
Greene 13890 0.11
Grundy 50155 0.39
Hamilton 8446 0.07
Hancock 19091 0.15
Hardin 4316 0.03
Henderson 7344 0.06
Henry 50459 0.39
Iroquois 29701 0.23
Jackson 60371 0.47
Jasper 9725 0.08
Jefferson 38757 0.30
Jersey 22997 0.18
Jo Daviess 22647 0.18
Johnson 12598 0.10
Kane 516060 4.02
Kankakee 113420 0.88
Kendall 115369 0.90
Knox 52911 0.41
Lake 704179 5.48
LaSalle 113812 0.89
Lawrence 16940 0.13
Lee 35978 0.28
Livingston 38862 0.30
Logan 30282 0.24
McDonough 32631 0.25
McHenry 309121 2.41
McLean 169815 1.32
Macon 110786 0.86
Macoupin 47798 0.37
Madison 269315 2.10
Marion 39416 0.31
Marshall 12637 0.10
Mason 14651 0.11
Massac 15380 0.12
Menard 12696 0.10
Mercer 16410 0.13
Monroe 33051 0.26
Montgomery 30095 0.23
Morgan 35499 0.28
Moultrie 14863 0.12
Ogle 53420 0.42
Peoria 186224 1.45
Perry 22316 0.17
Piatt 16710 0.13
Pike 16395 0.13
Pope 4477 0.04
Pulaski 6131 0.05
Putnam 6014 0.05
Randolph 33410 0.26
Richland 16193 0.13
Rock Island 147613 1.15
St. Clair 270368 2.11
Saline 24900 0.19
Sangamon 197769 1.54
Schuyler 7534 0.06
Scott 5330 0.04
Shelby 22354 0.17
Stark 5970 0.05
Stephenson 47606 0.37
Tazewell 135487 1.06
Union 17729 0.14
Vermilion 81642 0.64
Wabash 11916 0.09
Warren 17710 0.14
Washington 14711 0.12
Wayne 16739 0.13
White 14598 0.11
Whiteside 58489 0.46
Will 678829 5.29
Williamson 66440 0.52
Winnebago 295090 2.30
Woodford 38662 0.30