Illinois Population By County in 2012

Updated on January 29, 2024.

Based on the US Census Vintage data estimates, in 2012, the population of Illinois was 12,883,029. Among all Illinois counties, Cook had the highest population (5,239,105), followed by DuPage (928,719), and Lake (702,117). Hardin was the least populated county (4,278).

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 2012
Illinois Population By County in 2012
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County Population % of State Population
Adams 67149 0.52
Alexander 7721 0.06
Bond 17538 0.14
Boone 53729 0.42
Brown 6893 0.05
Bureau 34350 0.27
Calhoun 4983 0.04
Carroll 15121 0.12
Cass 13427 0.10
Champaign 204697 1.59
Christian 34522 0.27
Clark 16265 0.13
Clay 13710 0.11
Clinton 37908 0.29
Coles 53333 0.41
Cook 5239105 40.67
Crawford 19594 0.15
Cumberland 10955 0.09
DeKalb 104385 0.81
De Witt 16490 0.13
Douglas 19881 0.15
DuPage 928719 7.21
Edgar 18170 0.14
Edwards 6725 0.05
Effingham 34270 0.27
Fayette 22167 0.17
Ford 13877 0.11
Franklin 39872 0.31
Fulton 36585 0.28
Gallatin 5391 0.04
Greene 13657 0.11
Grundy 50161 0.39
Hamilton 8387 0.07
Hancock 18830 0.15
Hardin 4278 0.03
Henderson 7048 0.06
Henry 50263 0.39
Iroquois 29270 0.23
Jackson 59081 0.46
Jasper 9674 0.08
Jefferson 38672 0.30
Jersey 22717 0.18
Jo Daviess 22542 0.18
Johnson 12851 0.10
Kane 520615 4.04
Kankakee 112995 0.88
Kendall 118255 0.92
Knox 52302 0.41
Lake 702117 5.45
LaSalle 112913 0.88
Lawrence 16732 0.13
Lee 35218 0.27
Livingston 38519 0.30
Logan 30359 0.24
McDonough 32567 0.25
McHenry 308248 2.39
McLean 172762 1.34
Macon 110162 0.86
Macoupin 47058 0.37
Madison 268124 2.08
Marion 39018 0.30
Marshall 12261 0.10
Mason 14322 0.11
Massac 15067 0.12
Menard 12692 0.10
Mercer 16165 0.13
Monroe 33320 0.26
Montgomery 29620 0.23
Morgan 35318 0.27
Moultrie 14876 0.12
Ogle 52788 0.41
Peoria 187354 1.45
Perry 21849 0.17
Piatt 16505 0.13
Pike 16233 0.13
Pope 4464 0.04
Pulaski 5965 0.05
Putnam 5911 0.05
Randolph 33023 0.26
Richland 16132 0.13
Rock Island 147699 1.15
St. Clair 268748 2.09
Saline 24913 0.19
Sangamon 199431 1.55
Schuyler 7456 0.06
Scott 5290 0.04
Shelby 22204 0.17
Stark 5742 0.05
Stephenson 46895 0.36
Tazewell 136149 1.06
Union 17609 0.14
Vermilion 80881 0.63
Wabash 11690 0.09
Warren 17742 0.14
Washington 14598 0.11
Wayne 16668 0.13
White 14524 0.11
Whiteside 57772 0.45
Will 682459 5.30
Williamson 66793 0.52
Winnebago 292128 2.27
Woodford 38846 0.30