Data / Rankings / Population density / Counties in Illinois

Counties in Illinois by population density

Cook County had the highest population density of 102 counties in 2021, at 2,119.1 inhabitants per km². Pope County had the lowest, at 3.9 inhabitants per km². The median was 17.4 inhabitants per km² and the figure for Illinois was 88.4 inhabitants per km². Source: the U.S. Census Bureau.

Highest2,119.1Cook County
Lowest3.9Pope County
Median17.4102 counties
Illinois88.4History

Top 40 counties, 2021

CSVChart (SVG)

Cook CountyCook County: 2,119.1 inhabitants per km²2,119.1DuPage CountyDuPage County: 1,092.3 inhabitants per km²1,092.3Lake CountyLake County: 621.1 inhabitants per km²621.1Kane CountyKane County: 384.1 inhabitants per km²384.1Will CountyWill County: 323.3 inhabitants per km²323.3Winnebago CountyWinnebago County: 213.3 inhabitants per km²213.3McHenry CountyMcHenry County: 199.5 inhabitants per km²199.5Kendall CountyKendall County: 162.8 inhabitants per km²162.8St. Clair CountySt. Clair County: 149.8 inhabitants per km²149.8Madison CountyMadison County: 143.1 inhabitants per km²143.1Rock Island CountyRock Island County: 128.7 inhabitants per km²128.7Peoria CountyPeoria County: 112.4 inhabitants per km²112.4Sangamon CountySangamon County: 87.2 inhabitants per km²87.2Champaign CountyChampaign County: 80.2 inhabitants per km²80.2Tazewell CountyTazewell County: 78 inhabitants per km²78Boone CountyBoone County: 73.1 inhabitants per km²73.1Macon CountyMacon County: 68.2 inhabitants per km²68.2DeKalb CountyDeKalb County: 61.8 inhabitants per km²61.8Williamson CountyWilliamson County: 61.5 inhabitants per km²61.5Kankakee CountyKankakee County: 61 inhabitants per km²61McLean CountyMcLean County: 55.9 inhabitants per km²55.9Grundy CountyGrundy County: 48.9 inhabitants per km²48.9LaSalle CountyLaSalle County: 37 inhabitants per km²37Coles CountyColes County: 36.2 inhabitants per km²36.2Franklin CountyFranklin County: 35.4 inhabitants per km²35.4Monroe CountyMonroe County: 35.1 inhabitants per km²35.1Jackson CountyJackson County: 35.1 inhabitants per km²35.1Vermilion CountyVermilion County: 31.5 inhabitants per km²31.5Whiteside CountyWhiteside County: 31.2 inhabitants per km²31.2Stephenson CountyStephenson County: 30.2 inhabitants per km²30.2Clinton CountyClinton County: 30.1 inhabitants per km²30.1Adams CountyAdams County: 29.4 inhabitants per km²29.4Woodford CountyWoodford County: 28 inhabitants per km²28Effingham CountyEffingham County: 27.8 inhabitants per km²27.8Knox CountyKnox County: 26.6 inhabitants per km²26.6Ogle CountyOgle County: 26.2 inhabitants per km²26.2Marion CountyMarion County: 25.2 inhabitants per km²25.2Jefferson CountyJefferson County: 24.9 inhabitants per km²24.9Saline CountySaline County: 23.8 inhabitants per km²23.8Henry CountyHenry County: 23 inhabitants per km²23
inhabitants per km². Source: Invokely calculation with data from U.S. Census Bureau. Retrieved 2026-10-09.

Full ranking

RankCounties2021
inhabitants per km²		Change on 2020
1Cook County2,119.1-1.5%
2DuPage County1,092.3-0.4%
3Lake County621.1+0.1%
4Kane County384.1+0.1%
5Will County323.3+0.4%
6Winnebago County213.3-0.5%
7McHenry County199.5+0.6%
8Kendall County162.8+2%
9St. Clair County149.8-0.7%
10Madison County143.1-0.2%
11Rock Island County128.7-1.3%
12Peoria County112.4-0.8%
13Sangamon County87.2-0%
14Champaign County80.2+0.3%
15Tazewell County78-0.5%
16Boone County73.1-0.3%
17Macon County68.2-1.1%
18DeKalb County61.8+0.7%
19Williamson County61.5-0.3%
20Kankakee County61-0.4%
21McLean County55.9+0.1%
22Grundy County48.9+0.9%
23LaSalle County37-0.7%
24Coles County36.2+1.2%
25Franklin County35.4-0.6%
26Monroe County35.1+0.2%
27Jackson County35.1-0.4%
28Vermilion County31.5-1.1%
29Whiteside County31.2-0.5%
30Stephenson County30.2-0.9%
31Clinton County30.10%
32Adams County29.4-0.7%
33Woodford County28-0.5%
34Effingham County27.8-0.5%
35Knox County26.6-1%
36Ogle County26.2-0.4%
37Marion County25.2-0.7%
38Jefferson County24.9-0.3%
39Saline County23.8-1.5%
40Henry County23-0.5%
41Massac County22.7-1.3%
42Morgan County22.6-0.6%
43Jersey County22.3-0.6%
44Randolph County20.3+0.4%
45Macoupin County20-0.7%
46Wabash County19.4-0.8%
47Christian County18.3-0.7%
48Douglas County18.3-0.3%
49Lee County18.1-0.2%
50Perry County18.1-1%
51McDonough County17.8-0%
52Bond County17.1-0.3%
53Logan County17-2.3%
54Richland County16.9-0.1%
55Moultrie County16.7+0.5%
56Union County15.9-1.4%
57Crawford County15.9-2%
58Lawrence County15.6-1.4%
59Montgomery County15.4-0.4%
60Johnson County15.1+1.2%
61De Witt County15-0.3%
62Menard County15-0.8%
63Fulton County14.9-0.6%
64Piatt County14.7+0.5%
65Bureau County14.7-0.7%
66Jo Daviess County14.1-0.3%
67Carroll County13.6+0.2%
68Putnam County13.5-0.7%
69Livingston County13.3+0.1%
70Cass County13.1-1.5%
71Clark County11.8-0.5%
72Warren County11.8-1.3%
73Marshall County11.6-0.4%
74Cumberland County11.6-0.7%
75Fayette County11.4-1.9%
76Clay County10.9-0.8%
77White County10.7-0.4%
78Ford County10.7-0.2%
79Mercer County10.7-0.3%
80Shelby County10.6-0.2%
81Edwards County10.6-2%
82Edgar County10.3-1.2%
83Pulaski County9.9-1.6%
84Washington County9.4-0.5%
85Iroquois County9.3-0.7%
86Mason County9.2-1.7%
87Wayne County8.6-1%
88Hancock County8.5-0.9%
89Greene County8.4-0.7%
90Alexander County8.2-2.8%
91Brown County8.1+3.3%
92Hardin County7.9-0.2%
93Scott County7.7-1.8%
94Jasper County7.2-0.5%
95Stark County7.1-1.8%
96Hamilton County7-1%
97Pike County6.8-0.2%
98Calhoun County6.7-0.2%
99Henderson County6.4-0.4%
100Schuyler County6-0.5%
101Gallatin County5.9-0.7%
102Pope County3.9+0.1%

Other periods

About this ranking

Resident population divided by land area in km². World Bank figures use mid-year population and land area excluding inland water.

United States: Census Bureau population estimates for 1 July divided by land area (water excluded) from the latest Census Gazetteer files. US tables often give people per square mile; multiply persons per km² by 2.59 to compare.

Every value in the ranking comes from the same publisher and the same period, so the counties are compared on one definition. Equal values share a rank.

How to cite

U.S. Census Bureau. Population Estimates Program resident population on 1 July divided by land area from the latest Census Gazetteer files, persons per km². https://www2.census.gov/programs-surveys/popest/datasets/2020-2025/. Retrieved 2026-10-09.

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Rank Counties in Illinois by population density using official data, and cite the source.
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Questions

Which county has the highest population density?

Cook County, with 2,119.1 inhabitants per km² in 2021, according to the U.S. Census Bureau.

Which county has the lowest population density?

Pope County, with 3.9 inhabitants per km² in 2021.

Where does this ranking come from?

Every value comes from one source and one period, so the places are comparable: U.S. Census Bureau, Population Estimates Program resident population on 1 July divided by land area from the latest Census Gazetteer files, persons per km². Retrieved 2026-10-09.

Population density: other rankings

Counties in Illinois: more rankings