Private company

Cook County

County in Illinois, United States

Cook County is the most populous county in the U.S. state of Illinois and the second-most-populous county in the United States, after Los Angeles County, California. More than 40 percent of all residents of Illinois live within Cook County. As of 2020, the population was 5,275,541.2 Wikipedia text CC BY-SA 4.0

Last updated Oct 21, 2026.

Overview

Jan 15, 1831Founded1
Daley Plaza 060716
Photo: User:JeremyA, CC BY-SA 2.5, via Wikimedia Commons5

Cook County is the most populous county in the U.S. state of Illinois and the second-most-populous county in the United States, after Los Angeles County, California. More than 40 percent of all residents of Illinois live within Cook County. As of 2020, the population was 5,275,541. The county seat is Chicago, the most populous city in Illinois and the third most populous city in the United States. The county is at the center of the Chicago metropolitan area.2

The story

History

Cook County was created on January 15, 1831, out of Putnam County by an act of the Illinois General Assembly. It was the 54th county established in Illinois and was named after Daniel Pope Cook. As a politician, lawyer and newspaper publisher from the U.S. state of Illinois as well as an anti-slavery advocate, Cook became one of the earliest and youngest statesmen in Illinois history. He served as the second U.S. representative from Illinois and the state's first attorney general. In 1839, DuPage County was carved out of Cook County.

The shape of Cook County and the neighboring counties has remained the same since DuPage County was formed. The population in each county and the split of agriculture compared to residential and industrial activity has changed dramatically over the intervening decades to 2020. The county began with 10,201 people in the census of 1840, growing rapidly to 5,150,233 people estimated for 2019 by the US census. Growth was rapid in the 19th century, with the County reaching 2.4 million people by 1910. In the 20th century, the County reached 5.1 million population.

Cook County is nearly completely developed, with little agricultural land remaining near the outer county boundaries.

2020 census

As of the 2020 census, the county had a population of 5,275,541. The median age was 37.4 years. 20.9% of residents were under the age of 18 and 15.1% of residents were 65 years of age or older. For every 100 females there were 94.0 males, and for every 100 females age 18 and over there were 91.5 males age 18 and over.

The racial makeup of the county was 44.5% White, 22.9% Black or African American, 1.1% American Indian and Alaska Native, 7.8% Asian, <0.1% Native Hawaiian and Pacific Islander, 13.4% from some other race, and 10.4% from two or more races. Hispanic or Latino residents of any race comprised 26.2% of the population.

99.9% of residents lived in urban areas, while 0.1% lived in rural areas.

There were 2,086,940 households in the county, of which 28.4% had children under the age of 18 living in them. Of all households, 38.5% were married-couple households, 21.5% were households with a male householder and no spouse or partner present, and 33.2% were households with a female householder and no spouse or partner present. About 32.5% of all households were made up of individuals and 10.9% had someone living alone who was 65 years of age or older.

There were 2,264,966 housing units, of which 7.9% were vacant. Among occupied housing units, 54.3% were owner-occupied and 45.7% were renter-occupied. The homeowner vacancy rate was 1.7% and the rental vacancy rate was 7.5%.

Read the full text

2010 census

As of the 2010 Census, the population of the county was 5,194,675, White Americans made up 55.4% of Cook County's population; non-Hispanic whites represented 43.9% of the population. African Americans made up 24.8% of the population. Native Americans made up 0.4% of Cook County's population. Asian Americans made up 6.2% of the population (1.8% Indian, 1.2% Filipino, 1.2% Chinese, 0.7% Korean, 0.3% Vietnamese, 0.2% Japanese, 0.8% Other). Pacific Islander Americans made up less than 0.1% of the population. People from other races made up 10.6% of the population; people from two or more races made up 2.5% of the county's population. Hispanics and Latinos (of any race) made up 24.0% of Cook County's population.

2000 census

According to the 2000 Census there were 1,974,181 households, out of which 30.9% had children under the age of 18 living with them, 44.0% were married couples living together, 15.6% had a female householder with no husband present, and 35.7% were non-families. 29.4% of all households were someone living alone including 9.3% who were 65 years of age or older. The average household size was 2.68 and the average family size was 3.38.

In the county, the population age distribution was: 26.0% under the age of 18, 9.9% from 18 to 24, 31.7% from 25 to 44, 20.7% from 45 to 64, and 11.7% who were 65 years of age or older. The median age was 34 years. For every 100 females, there were 93.9 males. For every 100 females age 18 and over, there were 90.5 males.

The median income for a household in the county was $45,922, and the median income for a family was $53,784. Males had a median income of $40,690 versus $31,298 for females. The per capita income for the county was $23,227. About 10.6% of families and 13.5% of the population were below the poverty line, including 18.9% of those under age 18 and 10.3% of those age 65 or over.

As of the fourth quarter of 2021, the median home value in Cook County was $299,571, an increase of 11.7% from the prior year.

According to Census Bureau estimates, the county's population grew by 5.3% from 1990 to 2000, decreased by 3.4% between the 2000 census and the 2010 census, and increased 1.6% between 2010 and 2020.

As of the 2000 Census, there were 5,376,741 people, 1,974,181 households, and 1,269,398 families residing in the county. The population density was 5,686 inhabitants per square mile (2,195/km2). There were 2,096,121 housing units at an average density of 2,216 per square mile (856/km2). The racial makeup of the county was 56.27% white, 26.14% Black or African American, 0.29% Native American, 4.84% Asian, 0.05% Pacific Islanders, 9.88% from other races, and 2.53% from two or more races. 19.93% of the population were Hispanic or Latino of any race. 9.1% were of Polish, 8.1% German, 7.9% Irish and 5.7% Italian ancestry. 17.63% reported speaking Spanish at home; 3.13% speak Polish.

Whites (Hispanic and non-Hispanic) number roughly 2,793,500. There are about 2,372,500 non-Hispanic whites residing in Cook County. Sizeable non-Hispanic white populations are those of German (11.4%), Irish (10.3%), Polish (9.7%), Italian (6.1%), and British (4.1%) descent. There are also significant groups of Swedish (1.5%), Russian (1.5%), French (1.3%), Greek (1.2%), Czech (1.0%), Dutch (1.0%), Lithuanian (0.9%), and Norwegian (0.8%) descent.

Cook County has more Black residents than any county in the United States. Black Americans are the second largest racial group in the county, accounting for slightly over one-quarter (25.4%) of Cook County's population. Blacks of non-Hispanic origin form 25.2% of the population; black Hispanics make up the remaining 0.2% of the populace. There are roughly 1,341,000 African Americans of both Hispanic and non-Hispanic origin living in Cook County; 1,328,000 are non-Hispanic blacks. Roughly 52,500 people were of Sub-Saharan African ancestry, making up 1.0% of the total population.

Approximately 10,300 residents of Cook County are of Native American ancestry. They consist of Cherokee, Chippewa, Navajo, and Sioux. Native Americans of Hispanic origin represent a sizeable portion of the Native American population. Nearly 6,000 Native Americans are of non-Hispanic origin, and some 4,300 are of Hispanic origin. Over 40% of the Native American racial group is of Hispanic descent.

Asian Americans are a very sizeable racial group in the county, numbering about 301,000. The Asian population is ethnically diverse, and includes roughly 87,900 Indians, 61,700 Filipinos, 60,700 Chinese, 35,000 Koreans, 13,700 Vietnamese, and 11,100 Japanese. Roughly 30,800 are of other Asian ethnic groups, such as Thai, Cambodian, and Hmong.

Approximately 3,000 residents are of Pacific Islander heritage. This group includes roughly Native Hawaiians, Guamanians, Samoans, and various people of other Pacific Islander groups.

Hispanic and Latino Americans make up over one-fifth (22.8%) of Cook County's population. Roughly 1,204,000 Latinos live in the county. Mexicans are the most common Latino group. Cook County's 925,000 Mexican Americans make up 17.5% of its population. Roughly 127,000 Puerto Ricans live in the county, while over 12,200 Cubans reside in the county. There are some 140,000 Hispanics and Latinos of other nationalities living in Cook County (i.e. Colombian, Bolivian, etc.), and they collectively make up 2.6% of the county's population.

From Wikipedia’s article on Cook County, Illinois, shared under CC BY-SA 4.0.4

Timeline

  1. Jan 15, 1831Founded Founded1

Sources

The numbers on this page point here. Each one links to the record it came from.

  1. 1
  2. 2
  3. 3
  4. 4
  5. 5