Data / Rankings / Population density / Counties in Illinois

Counties in Illinois by population density

Cook County had the highest population density of 102 counties in 2024, at 2,120.2 inhabitants per km². Pope County had the lowest, at 3.9 inhabitants per km². The median was 17.1 inhabitants per km² and the figure for Illinois was 88.4 inhabitants per km². Source: the U.S. Census Bureau.

Highest2,120.2Cook County
Lowest3.9Pope County
Median17.1102 counties
Illinois88.4History

Top 40 counties, 2024

CSVChart (SVG)

Cook CountyCook County: 2,120.2 inhabitants per km²2,120.2DuPage CountyDuPage County: 1,098.2 inhabitants per km²1,098.2Lake CountyLake County: 625.3 inhabitants per km²625.3Kane CountyKane County: 389.1 inhabitants per km²389.1Will CountyWill County: 327.5 inhabitants per km²327.5Winnebago CountyWinnebago County: 212.9 inhabitants per km²212.9McHenry CountyMcHenry County: 202 inhabitants per km²202Kendall CountyKendall County: 172.6 inhabitants per km²172.6St. Clair CountySt. Clair County: 147.6 inhabitants per km²147.6Madison CountyMadison County: 142.1 inhabitants per km²142.1Rock Island CountyRock Island County: 127.9 inhabitants per km²127.9Peoria CountyPeoria County: 111.4 inhabitants per km²111.4Sangamon CountySangamon County: 86.3 inhabitants per km²86.3Champaign CountyChampaign County: 81.1 inhabitants per km²81.1Tazewell CountyTazewell County: 77.6 inhabitants per km²77.6Boone CountyBoone County: 73.6 inhabitants per km²73.6Macon CountyMacon County: 66.5 inhabitants per km²66.5Williamson CountyWilliamson County: 61.6 inhabitants per km²61.6DeKalb CountyDeKalb County: 61.5 inhabitants per km²61.5Kankakee CountyKankakee County: 60.4 inhabitants per km²60.4McLean CountyMcLean County: 56 inhabitants per km²56Grundy CountyGrundy County: 49.6 inhabitants per km²49.6LaSalle CountyLaSalle County: 36.7 inhabitants per km²36.7Coles CountyColes County: 35.4 inhabitants per km²35.4Monroe CountyMonroe County: 35.2 inhabitants per km²35.2Franklin CountyFranklin County: 34.9 inhabitants per km²34.9Jackson CountyJackson County: 34.9 inhabitants per km²34.9Whiteside CountyWhiteside County: 30.7 inhabitants per km²30.7Vermilion CountyVermilion County: 30.7 inhabitants per km²30.7Clinton CountyClinton County: 30.2 inhabitants per km²30.2Stephenson CountyStephenson County: 29.7 inhabitants per km²29.7Adams CountyAdams County: 29 inhabitants per km²29Woodford CountyWoodford County: 28 inhabitants per km²28Effingham CountyEffingham County: 27.9 inhabitants per km²27.9Ogle CountyOgle County: 26.1 inhabitants per km²26.1Knox CountyKnox County: 25.9 inhabitants per km²25.9Marion CountyMarion County: 24.6 inhabitants per km²24.6Jefferson CountyJefferson County: 24.4 inhabitants per km²24.4Saline CountySaline County: 23.2 inhabitants per km²23.2Henry CountyHenry County: 22.6 inhabitants per km²22.6
inhabitants per km². Source: Invokely calculation with data from U.S. Census Bureau. Retrieved 2026-10-09.

Full ranking

RankCounties2024
inhabitants per km²		Change on 2023
1Cook County2,120.2+0.9%
2DuPage County1,098.2+0.6%
3Lake County625.3+0.7%
4Kane County389.1+1%
5Will County327.5+0.7%
6Winnebago County212.9+0.4%
7McHenry County202+0.7%
8Kendall County172.6+2.1%
9St. Clair County147.6-0.3%
10Madison County142.1-0%
11Rock Island County127.9+0.5%
12Peoria County111.4+0.2%
13Sangamon County86.30%
14Champaign County81.1+0.3%
15Tazewell County77.6-0%
16Boone County73.6+0.3%
17Macon County66.5-0.4%
18Williamson County61.6+0.5%
19DeKalb County61.5+0.5%
20Kankakee County60.4-0%
21McLean County56+0.3%
22Grundy County49.6+0.3%
23LaSalle County36.70%
24Coles County35.4-0.2%
25Monroe County35.2-0.2%
26Franklin County34.9-0.4%
27Jackson County34.9+0.3%
28Whiteside County30.7-0.1%
29Vermilion County30.7-0.3%
30Clinton County30.2+0.4%
31Stephenson County29.7-0.2%
32Adams County29-0.5%
33Woodford County28-0.3%
34Effingham County27.9+0.3%
35Ogle County26.1-0.2%
36Knox County25.9-0.5%
37Marion County24.6-0.4%
38Jefferson County24.4-0.5%
39Saline County23.2-0.7%
40Henry County22.6-0.3%
41Massac County22.2-0.9%
42Morgan County22.1-0.5%
43Jersey County22.1-0.1%
44Randolph County20+0.2%
45Macoupin County19.6-0.3%
46Wabash County19.1-0.4%
47Douglas County18.4+0.5%
48Christian County18.2-0.2%
49Perry County17.8-1.4%
50Lee County17.5-0%
51McDonough County17.1-2.6%
52Logan County17+0.7%
53Bond County16.9-0.2%
54Moultrie County16.6+0.7%
55Richland County16.5-0.9%
56Crawford County16.2+1.1%
57Union County15.7-0.2%
58Montgomery County15.3+0.2%
59Johnson County15-0.1%
60De Witt County14.8-0.3%
61Menard County14.6-0.7%
62Fulton County14.6-0.2%
63Piatt County14.6-0.6%
64Bureau County14.4-0.7%
65Lawrence County14.3+0.8%
66Jo Daviess County13.9-0.7%
67Putnam County13.5+0.7%
68Carroll County13.4-0.5%
69Livingston County13-0.1%
70Cass County12.9-1.5%
71Clark County11.7-0.6%
72Marshall County11.5-0.8%
73Warren County11.5-0.3%
74Cumberland County11.50%
75Fayette County11.3-0.4%
76Ford County10.6+0.4%
77Clay County10.6-0.8%
78Mercer County10.5-1.2%
79White County10.5-0.4%
80Shelby County10.5-0.2%
81Edwards County10.4-0.6%
82Edgar County10.1-0.3%
83Pulaski County9.5-1.7%
84Washington County9.30%
85Iroquois County9.1+0.3%
86Mason County8.9-0.7%
87Wayne County8.6+0.3%
88Hancock County8.2-1.5%
89Brown County8.1-0.7%
90Greene County8.1-1.5%
91Hardin County7.8-0.4%
92Alexander County7.6-2.5%
93Scott County7.5+0.5%
94Jasper County7.1-1.1%
95Stark County7.1+0.1%
96Hamilton County7-0.4%
97Pike County6.6-0.5%
98Calhoun County6.6-0.4%
99Henderson County6.1-1.2%
100Schuyler County5.9+0.2%
101Gallatin County5.6-0.3%
102Pope County3.9+0.2%

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 2,120.2 inhabitants per km² in 2024, according to the U.S. Census Bureau.

Which county has the lowest population density?

Pope County, with 3.9 inhabitants per km² in 2024.

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