Illinois Citizen Population By County in 2020 (ACS-5Yrs)

Updated on March 28, 2026.

Based on the US Census Bureau's special tabulation from the ACS 5-year estimates, in 2020, the citizen population for Illinois was 11,866,595 and represented 93.32% of the total Illinois population.

Among all Illinois counties, Cook had the highest citizen population (4.65M), followed by DuPage (852.38K), and Will (654.45K).

In terms of percentages, Alexander had the highest percentage of its population being citizens (100.00%), followed by Clay (99.92%), and Calhoun (99.90%).

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 2020

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

See this for other years:

Illinois Citizen Population By County in 2020

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County	Citizen Population	% of County Population
Cook	4651775	89.99
DuPage	852375	92.05
Will	654450	94.89
Lake	637355	91.09
Kane	483495	90.92
McHenry	295025	96.01
Winnebago	270435	95.35
Madison	261995	99.09
St. Clair	257305	98.51
Sangamon	193035	98.51
Champaign	192500	91.66
Peoria	175675	97.00
McLean	165315	96.02
Rock Island	136230	95.40
Tazewell	131305	99.08
Kendall	121500	95.23
LaSalle	106890	98.06
Kankakee	106810	97.17
Macon	103565	98.93
DeKalb	100475	96.07
Vermilion	75975	99.05
Williamson	66295	99.05
Adams	65460	99.68
Jackson	55240	96.05
Whiteside	54575	98.18
Boone	50480	94.72
Coles	50480	98.85
Grundy	49970	98.37
Ogle	49705	97.85
Knox	48770	97.44
Henry	48680	99.29
Macoupin	45055	99.58
Stephenson	44310	99.16
Franklin	38510	99.54
Woodford	38275	99.40
Jefferson	37545	99.39
Marion	37325	99.47
Clinton	37180	99.02
Livingston	35370	98.92
Fulton	34445	99.39
Monroe	34355	99.74
Lee	33715	98.57
Effingham	33685	98.64
Morgan	33640	98.91
Christian	32475	99.30
Bureau	32240	98.05
Randolph	31610	98.86
McDonough	29665	98.54
Logan	28560	99.10
Montgomery	28465	99.53
Iroquois	26935	98.18
Saline	23675	99.75
Jersey	21660	99.47
Shelby	21545	99.63
Fayette	21270	99.30
Jo Daviess	21160	98.74
Perry	20960	99.38
Douglas	19255	98.49
Crawford	18710	99.34
Hancock	17785	99.80
Edgar	17230	99.77
Union	16630	98.81
Warren	16470	97.00
Bond	16400	99.27
Piatt	16295	99.30
Wayne	16210	99.39
De Witt	15685	99.49
Lawrence	15670	98.99
Richland	15540	99.14
Clark	15535	99.58
Pike	15530	99.74
Mercer	15395	99.29
Moultrie	14500	99.62
Carroll	14325	99.48
Massac	13935	99.25
Washington	13925	99.71
White	13670	99.71
Mason	13460	99.82
Clay	13205	99.92
Ford	13075	99.39
Greene	12965	99.81
Johnson	12260	98.95
Menard	12215	99.63
Marshall	11470	99.22
Cass	11245	91.24
Wabash	11245	98.73
Cumberland	10730	99.49
Jasper	9470	99.21
Hamilton	8115	99.57
Schuyler	6825	98.99
Henderson	6705	99.56
Brown	6545	99.17
Edwards	6415	99.77
Alexander	6010	100.00
Putnam	5695	99.56
Pulaski	5385	99.45
Stark	5335	98.89
Gallatin	4975	99.80
Scott	4945	99.30
Calhoun	4775	99.90
Pope	4160	99.64
Hardin	3880	99.74