Cook County, Illinois Population 2026
Updated April 2026 · US Census ACS 2023 5-Year Estimates · 1st-largest in Illinois
The population of Cook County, Illinois is 5,185,812 as of the 2023 American Community Survey, making it the 1st-largest county in Illinois. The median household income is $81,797, the median home value is $305,200, and the median age is 37.8.
The population of Cook County has declined 0.3% since 2010 (5,198,977 → 5,182,617), a -0.02% annualized rate.
5,185,812
Population
-0.02%
Annual growth
5488
People / sq mi
$81,797
Median Income
$305,200
Median Home Value
Cook County covers 945 sq mi of land at 5488.1 people per square mile.
About Cook County, IL
What distinguishes Cook County is density: among the most densely settled of US counties, around 5,488 people per square mile. With 5,185,812 residents, Cook County is a county in Illinois. It is the #1-largest of all counties in Illinois nationally.
Households take in a median $81,797, comfortably near the US median of $78,538. About 9.8% of residents live below the federal poverty level, below the national 12.4%. Home values run above average at $305,200, with typical rent around $1,381.
The population is unusually well-credentialed for US counties — 41.9% of adults have a four-year degree, above the national 35.0%. An unusually large 16.5% of workers are remote, above the national 14.0%, and the average commute runs about 32 minutes each way.
That density explains much of the rest of the profile in Cook County: denser places lean toward renting, shorter commutes by transit, and a younger working-age mix.
Cook County Population History (2010-2024)
The county of Cook County had a population of 5,198,977 in 2010 and 5,182,617 in 2024, a -0.3% growth over 14 years. The peak was 5,267,072 in 2020. Average annual growth rate: -0.02%.
5,182,617
Population (2024)
5,198,977
Population (2010)
5,267,072
Peak (2020)
-0.02%
Avg Annual Growth
| Year | Population |
|---|---|
| 2010 | 5,198,977 |
| 2011 | 5,219,636 |
| 2012 | 5,239,105 |
| 2013 | 5,252,513 |
| 2014 | 5,254,108 |
| 2015 | 5,243,371 |
| 2016 | 5,223,386 |
| 2017 | 5,199,582 |
| 2018 | 5,171,007 |
| 2019 | 5,145,326 |
| 2020 | 5,267,072 |
| 2021 | 5,185,134 |
| 2022 | 5,133,106 |
| 2023 | 5,142,522 |
| 2024 | 5,182,617 |
Race & Ethnicity
| White | 46.4% |
| Black or African American | 22.5% |
| Asian | 0.0% |
| Hispanic or Latino (any race) | 1.7% |
| Two or More Races | 0.0% |
Age & Sex
37.8
Median Age
51.2%
Female
48.8%
Male
15.6%
Age 65+
Age Distribution
Children (under 15): 17.6% · Seniors (65+): 15.6%
Income & Poverty
| Median household income | $81,797+$95 vs state |
| Mean household income | $117,699 |
| Per-capita income | $47,801 |
| Poverty rate | 9.8%+1.6% vs state |
| Unemployment rate | 4.5% |
| Employment-to-population | 61.6% |
Top Industries by Employment
The largest employment sector in Cook County is professional & business services, accounting for 23.5% of workers.
How residents commute
13.0%
Drive alone
3.9%
Carpool
56.2%
Public transit
16.5%
Work from home
31.9 min
Avg commute
Housing
$305,200+$54,700 vs state
Median home value
$1,381
Median rent
57.5%
Homeownership rate
2,270,349
Total housing units
91.8%
Occupied
8.2%
Vacant
42.5%
Renter-occupied
Social & access
91.0%
With health insurance
94.4%
With broadband internet
15.7%
Foreign-born
3.3%
Veterans (18+)
11.2%
With a disability
64.5%
Speak language other than English at home
Education
88.3%
High School+
41.9%
Bachelor's+
Largest cities in Illinois
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County rankings
Common questions about Cook County, IL
Frequently Asked Questions
Cook County, Illinois has a population of 5,185,812 according to the US Census Bureau's 2023 American Community Survey 5-year estimates, making it the 1st-largest county in Illinois. Population density is 5488 people per square mile.
The population of Cook County has declined 0.3% since 2010 (5,198,977 → 5,182,617), a -0.02% annualized rate.
The median household income in Cook County, Illinois is $81,797, with mean (average) household income of $117,699 and per-capita income of $47,801. 9.8% of residents live below the federal poverty level.
In Cook County, the largest racial and ethnic groups are White (46.4%), Black or African American (22.5%), Hispanic or Latino (1.7%). Figures are from the US Census Bureau's 2023 ACS 5-year estimates and reflect self-reported responses.
The median age in Cook County, Illinois is 37.8 years. Residents are 51.2% female and 48.8% male.
The median home value in Cook County is $305,200 and median monthly rent is $1,381. 57.5% of occupied housing units are owner-occupied. The county has 2,270,349 total housing units, 8.2% of which are vacant.
The largest employment sector in Cook County, Illinois is professional, scientific, and management services, employing 23.5% of workers. The unemployment rate is 4.5%.
Chicago is among the largest cities associated with Cook County, Illinois, with a population of 2,707,648.
Cook County, IL Climate
Cook County, IL has an average annual temperature of 9.9°C (50°F) and receives about 942 mm of precipitation per year. The warmest month is July and the coldest is January. Figures are 1970–2000 climate normals.
9.9°C
Avg Temp
942
Precip (mm/yr)
Jul
Hottest Month
Jan
Coldest Month
| Month | Avg (°C/°F) | Precip |
|---|---|---|
| January | -5° / 23° | 46 mm |
| February | -2° / 28° | 40 mm |
| March | 3° / 37° | 67 mm |
| April | 9° / 48° | 96 mm |
| May | 15° / 59° | 92 mm |
| June | 21° / 69° | 101 mm |
| July | 23° / 74° | 94 mm |
| August | 22° / 72° | 100 mm |
| September | 18° / 65° | 91 mm |
| October | 12° / 53° | 70 mm |
| November | 5° / 41° | 80 mm |
| December | -2° / 29° | 65 mm |
1970–2000 normals from WorldClim 2.1 (~9 km grid). Precipitation can be less precise near mountains or coastlines, where rainfall varies sharply over short distances.
Best time to visit Cook County, IL
The most comfortable months to visit Cook County, IL are typically June, August and July, when temperatures are mildest and rainfall is relatively low. The hottest month is July (around 29°C high). The coldest is January (near -9°C low). June is usually the wettest month.
Where to stay near Cook County
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Data from the American Community Survey (ACS) 5-Year estimates.
Source: U.S. Census Bureau ACS, 2026.