Illinois Citizen Population By County in 2021 (ACS-5Yrs)

Updated on March 28, 2026.

Based on the US Census Bureau's special tabulation from the ACS 5-year estimates, in 2021, the citizen population for Illinois was 11,967,340 and represented 93.34% of the total Illinois population.

Among all Illinois counties, Cook had the highest citizen population (4.74M), followed by DuPage (859.81K), and Will (660.29K).

In terms of percentages, Calhoun had the highest percentage of its population being citizens (100.00%), followed by Alexander (99.91%), and Clay (99.89%).

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 2021

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

See this for other years:

Illinois Citizen Population By County in 2021

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County	Citizen Population	% of County Population
Cook	4743370	90.09
DuPage	859810	92.05
Will	660290	94.81
Lake	651405	91.17
Kane	472500	91.10
McHenry	297930	95.87
Winnebago	271965	95.27
Madison	263960	99.19
St. Clair	254930	98.58
Sangamon	193835	98.51
Champaign	189425	91.69
Peoria	176250	96.61
McLean	164485	95.94
Rock Island	137880	95.29
Tazewell	131025	99.28
Kendall	124920	95.54
LaSalle	108050	98.24
Kankakee	105235	97.35
Macon	102955	98.68
DeKalb	96605	95.72
Vermilion	74265	99.08
Williamson	66580	98.97
Adams	65630	99.62
Whiteside	55000	98.34
Jackson	51705	96.33
Grundy	51415	98.19
Boone	50825	94.84
Ogle	50690	97.89
Henry	49030	99.23
Knox	48920	97.46
Coles	47065	99.00
Macoupin	44975	99.61
Stephenson	44470	99.23
Woodford	38305	99.31
Franklin	37950	99.69
Marion	37620	99.58
Jefferson	37085	99.26
Clinton	36580	98.73
Livingston	35555	99.04
Monroe	34630	99.71
Effingham	34160	98.80
Lee	33890	98.59
Fulton	33865	99.54
Christian	33835	99.40
Morgan	33005	99.44
Bureau	32725	98.16
Randolph	30095	98.25
Montgomery	28340	99.51
Logan	28045	99.31
McDonough	27420	98.83
Iroquois	26810	97.99
Saline	23775	99.60
Jo Daviess	21715	98.73
Fayette	21405	99.49
Jersey	21350	99.14
Shelby	21075	99.60
Perry	21025	99.36
Douglas	19425	98.55
Crawford	18710	99.39
Hancock	17625	99.30
Union	17120	99.19
Edgar	16960	99.77
Bond	16685	99.29
Piatt	16615	99.70
Warren	16430	97.31
Wayne	16025	98.62
Richland	15750	99.21
Mercer	15710	99.56
Clark	15535	99.68
De Witt	15510	99.07
Carroll	15425	98.97
Lawrence	15260	98.67
Pike	14855	99.53
Moultrie	14585	99.66
Massac	14155	99.13
White	13885	99.46
Washington	13780	99.68
Ford	13425	98.79
Clay	13300	99.89
Mason	13205	99.85
Johnson	13145	99.28
Menard	12285	99.51
Greene	12160	99.80
Cass	11920	91.27
Marshall	11695	99.28
Wabash	11285	98.86
Cumberland	10460	99.34
Jasper	9215	98.82
Hamilton	8010	99.88
Schuyler	6895	99.14
Henderson	6475	99.85
Brown	6280	99.21
Edwards	6215	99.68
Putnam	5630	99.82
Alexander	5485	99.91
Stark	5365	98.71
Pulaski	5265	99.72
Gallatin	5025	99.70
Scott	4890	99.29
Calhoun	4535	100.00
Pope	3800	99.48
Hardin	3690	99.73