Counties in Illinois by population density
Cook County had the highest population density of 102 counties in 2020, at 2,150.7 inhabitants per km². Pope County had the lowest, at 3.9 inhabitants per km². The median was 17.6 inhabitants per km² and the figure for Illinois was 89 inhabitants per km². Source: the U.S. Census Bureau.
Top 40 counties, 2020
Full ranking
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.Use this data in your AI agent
Invokely serves this figure to AI assistants through MCP and to code through a REST API, with the source and citation attached. Ask your assistant:
Rank Counties in Illinois by population density using official data, and cite the source.
rank_places {"indicator":"population_density","level":"province","within":"Illinois","limit":10}
GET https://invokely.ai/api/v1/rank?indicator=population_density&level=province&within=Illinois&limit=10Questions
Which county has the highest population density?
Cook County, with 2,150.7 inhabitants per km² in 2020, according to the U.S. Census Bureau.
Which county has the lowest population density?
Pope County, with 3.9 inhabitants per km² in 2020.
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
- Countries
- EU countries
- US states
- EU regions (NUTS 2)
- US counties
- Autonomous communities of Spain
- Provinces of Spain
- Municipalities of Spain
- Regions of Germany (NUTS 2)
- Regions of France (NUTS 2)
- Regions of Italy (NUTS 2)
- Regions of Poland (NUTS 2)
Counties in Illinois: more rankings
- Asian population share
- Bachelor's degree or higher, population 25 and over
- Live births, July to June
- Black or African American population share
- Crude birth rate, July to June
- Crude death rate, July to June
- Deaths, July to June
- Foreign-born population share
- Real GDP growth
- GDP per capita, US dollars
- Gross domestic product (GDP), US dollars
- Hispanic or Latino population share
- Homeownership rate (US, housing units)
- Median age
- Median gross rent (monthly)
- Median home value