Illinois Citizen Population By County in 2018 (ACS-5Yrs)

Updated on March 28, 2026.

Based on the US Census Bureau's special tabulation from the ACS 5-year estimates, in 2018, the citizen population for Illinois was 11,923,115 and represented 92.99% of the total Illinois population.

Among all Illinois counties, Cook had the highest citizen population (4.68M), followed by DuPage (856.80K), and Will (651.43K).

In terms of percentages, Gallatin had the highest percentage of its population being citizens (100.00%), followed by Hardin (100.00%), and Massac (99.86%).

The chart and table below shows the citizen population of each county and the percentage of each county's population that were citizens.

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

You may also be interested in:
Illinois Citizen Voting-age Population By County in 2018

Data Source: US Census - ACS 5-Year (CVAP).

See this for other years:

Illinois Citizen Population By County in 2018

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County	Citizen Population	% of County Population
Cook	4674575	89.49
DuPage	856795	91.96
Will	651430	94.59
Lake	637885	90.66
Kane	476480	89.76
McHenry	294810	95.78
Winnebago	273950	95.73
Madison	262795	98.92
St. Clair	259460	98.48
Sangamon	194450	98.38
Champaign	191900	91.62
Peoria	178595	96.82
McLean	165570	95.58
Rock Island	138315	95.21
Tazewell	132600	99.07
Kendall	119705	96.05
LaSalle	108340	98.13
Kankakee	107865	97.12
Macon	105465	99.02
DeKalb	99370	95.37
Vermilion	77430	98.76
Williamson	66785	99.24
Adams	66110	99.53
Jackson	56315	96.18
Whiteside	55450	98.32
Coles	50950	98.48
Boone	50435	94.09
Grundy	49885	98.76
Knox	49845	97.74
Ogle	49755	96.93
Henry	48945	98.95
Macoupin	45595	99.73
Stephenson	44935	98.90
Franklin	38970	99.60
Woodford	38745	99.82
Jefferson	37890	99.27
Marion	37805	99.27
Clinton	37265	99.03
Livingston	35860	98.72
Fulton	34945	98.66
Morgan	34075	98.98
Lee	34040	98.60
Monroe	33750	99.46
Effingham	33730	98.70
Christian	32990	99.28
Bureau	32640	97.78
Randolph	32265	99.14
McDonough	30050	97.33
Logan	28945	99.11
Montgomery	28925	99.71
Iroquois	27640	98.12
Saline	24180	99.79
Jersey	21900	99.23
Shelby	21790	99.82
Fayette	21630	99.56
Jo Daviess	21565	98.76
Perry	21270	99.46
Douglas	19355	98.17
Crawford	18925	99.14
Hancock	18045	99.64
Edgar	17435	99.40
Union	16830	98.28
Warren	16690	96.25
Bond	16480	98.62
Wayne	16405	99.52
Piatt	16335	99.45
Lawrence	15950	98.52
De Witt	15860	98.88
Pike	15730	99.84
Clark	15720	99.27
Mercer	15655	99.75
Richland	15650	98.55
Moultrie	14600	99.29
Carroll	14455	99.28
Massac	14410	99.86
Washington	14110	99.68
White	13945	99.43
Mason	13750	99.78
Ford	13335	99.52
Clay	13265	99.44
Greene	13175	99.66
Johnson	12470	98.97
Menard	12330	99.72
Marshall	11745	99.58
Cass	11605	91.63
Wabash	11415	98.62
Cumberland	10805	99.45
Jasper	9480	98.75
Hamilton	8185	99.57
Schuyler	6950	98.37
Henderson	6840	99.35
Brown	6560	98.28
Alexander	6505	99.62
Edwards	6495	99.85
Putnam	5680	98.87
Pulaski	5560	99.11
Stark	5450	99.09
Gallatin	5155	100.00
Scott	5020	99.50
Calhoun	4840	99.59
Pope	4235	99.65
Hardin	4010	100.00