Cook County was incorporated in 1831 and named forDaniel Pope Cook, an early Illinois statesman. It achieved its present boundaries in 1839. Within a century, the county recorded explosive population growth, going from a trading post village with a little over six hundred residents to four million, rivaling Paris by theGreat Depression. During the first half of the 20th century, it had the absolute majority of Illinois's population.
There are more than 800 local governmental units and nearly 130 municipalities located wholly or partially within Cook County, the largest of which is Chicago. The city is home to approximately 54 percent of the entire county's population.[6] The part of the county outside of the Chicago andEvanston city limits is divided into 29townships; these often divide or share governmental services with local municipalities. Townships within Chicago were abolished in 1902 but are retained for real estate assessment purposes.Evanston Township was formerly coterminous with the City of Evanston but was abolished in 2014. County government is overseen by theCook County Board of Commissioners, with its president as chief executive, andCook County Treasurer. Countywide state government offices include theCircuit Court of Cook County, theCook County State's Attorney, theCook County Sheriff, and theCook County Assessor.
Geographically, the county is the sixth-largest in Illinois by land area and the largest by total area. It shares the state'sLake Michigan shoreline withLake County. Including its lake area, Cook County has a total area of 1,635 square miles (4,234.6 km2), the largest county in Illinois, of which 945 square miles (2,447.5 km2) is land and 690 square miles (1,787.1 km2) (42.16%) is water. Land-use in Cook County is mostly urban and densely populated. Within Cook County, the state of Illinois took advantage of its Lake Michigan access and theChicago Portage, beginning with the construction of theIllinois and Michigan Canal in 1848. This helped make the region a central transit hub for the nation. Chicago, with its location on theGreat Lakes and via theSt. Lawrence Seaway, is a global port city, giving Cook County an international shipping port.
Cook County 1836–1839 after the creation ofMcHenry andWill counties
Cook County's current size was formed in 1839 by the creation ofDuPage 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 5,150,233people 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.[8]
U.S. Decennial Census[10] 1790–1960[11] 1900–1990[12] 1990–2000[13] 2010–2019[14]
According to the2000 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.
Ethnic origins in Cook County
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.[15]
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.
Cook County, Illinois – Racial and ethnic composition Note: the US Census treats Hispanic/Latino as an ethnic category. This table excludes Latinos from the racial categories and assigns them to a separate category. Hispanics/Latinos may be of any race.
Racial / Ethnic Profile of places in Cook County, Illinois (2020 Census)
Following is a table of towns and census designated places in Cook County, Illinois. Data for the United States (with and without Puerto Rico), the state of Illinois, and Cook County itself have been included for comparison purposes. The majority racial/ethnic group is coded per the key below. Communities that extend into and adjacent county or counties are delineated with a‡ followed by an accompanying explanatory note. The full population of each community has been tabulated including the population in adjacent counties.
Majority minority with no dominant group
Majority White
Majority Black
Majority Hispanic
Majority Asian
Racial and ethnic composition of places in Cook County, Illinois (2020 Census) (NH = Non-Hispanic) Note: the US Census treats Hispanic/Latino as an ethnic category. This table excludes Latinos from the racial categories and assigns them to a separate category. Hispanics/Latinos may be of any race.
As of the2010 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 fromtwo 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.
As of the2000 Census,[175] 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 wereHispanic 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% speakPolish.[176]
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 ofGerman (11.4%),Irish (10.3%),Polish (9.7%),Italian (6.1%), andBritish (4.1%) descent. There are also significant groups ofSwedish (1.5%),Russian (1.5%),French (1.3%),Greek (1.2%),Czech (1.0%),Dutch (1.0%),Lithuanian (0.9%), andNorwegian (0.8%) descent.
Cook County has more Black residents than any county in the United States.[177] 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 ofCherokee,Chippewa,Navajo, andSioux. 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.
Non-English speakers in Cook County
Asian Americans are a very sizeable racial group in the county, numbering about 301,000. The Asian population is ethnically diverse, and includes roughly 87,900Indians, 61,700Filipinos, 60,700Chinese, 35,000Koreans, 13,700Vietnamese, and 11,100Japanese. Roughly 30,800 are of other Asian ethnic groups, such asThai,Cambodian, andHmong.
Approximately 3,000 residents are of Pacific Islander heritage. This group includes roughlyNative 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 127,000Puerto Ricans live in the county, while over 12,200Cubans 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.[178][179]
In 2010 statistics, the largest religious group in Cook County was theArchdiocese of Chicago, with 1,947,223 Catholics worshipping at 371 parishes, followed by 209,195non-denominational adherents with 486 congregations, an estimated 201,152Muslims with 62 congregations, 68,865NBC Baptists with 99 congregations, 49,925ELCA Lutherans with 145 congregations, 49,909SBC Baptists with 181 congregations, 45,979LCMS Lutherans with 120 congregations, 39,866UCC Christians with 101 congregations, 33,584UMC Methodists with 121 congregations, and 32,646AG Pentecostals with 64 congregations. Altogether, 59.6% of the population was claimed as members by religious congregations, although members of historically African-American denominations were underrepresented due to incomplete information.[180] In 2014, Cook County had 2,001 religious organizations, second only toLos Angeles County out of all US counties.[181]
According to theU.S. Census Bureau, the county has a total area of 1,635 square miles (4,230 km2), of which 945 square miles (2,450 km2) is land and 690 square miles (1,800 km2) (42.2%) is water.[183] It is the sixth largest county in Illinois by land area, and the largest in total area. Most of the water is inLake Michigan. The highest point is more than 950 feet (290 m),[1][2] and is in northwest Barrington Township, in the northwest corner of the county. The lowest point is less than 580 feet (180 m),[1][3] along theLake Michigan shoreline.
In July, temperatures in Chicago, Cook County average daytime highs of 84 °F (29 °C), and nighttime lows of 68 °F (20 °C); and January daytime highs of 31 °F (−1 °C), and nighttime lows of 18 °F (−8 °C). Winter temperatures will sometimes veer above 40 °F (4 °C), and, although not common, have also risen over 50 °F (10 °C) on some winter days. Average monthly precipitation ranged from 4.30 inches (109 mm) in June to 1.77 inches (45 mm) in February.[182]
The government of Cook County is primarily composed of theBoard of Commissioners headed by the President of the County Board, other elected officials such as theSheriff,State's Attorney, Treasurer, Board of Review, Clerk, Assessor, Recorder,Circuit Court judges, and Circuit Court Clerk, as well as numerous other officers and entities. Cook County is the onlyhome rule county in Illinois.[184] TheCook County Code is thecodification of Cook County'slocal ordinances. Cook County's currentCounty Board president isToni Preckwinkle.
TheCircuit Court of Cook County, which is an Illinois state court ofgeneral jurisdiction is funded, in part, by Cook County, and accepts more than 1.2 million cases each year for filing.[185] TheCook County Department of Corrections, also known as theCook County Jail, is the largest single-site jail in the nation. TheCook County Juvenile Detention Center, under the authority of the Chief Judge of the court, is the first juvenile center in the nation and one of the largest in the nation. The Cook County Law Library is the second-largest county law library in the nation.
The Cook County Department of Transportation is responsible for the design and maintenance of roadways in the county. These thoroughfares are composed mostly of major and minor arterials, with a few local roads. Although the County Department of Transportation was instrumental in designing many of the expressways in the county, today they are under the jurisdiction of the state.
TheCook County Forest Preserves, organized in 1915, is a separate, independent taxing body, but the Cook County Board of Commissioners also acts as its Board of Commissioners. The district is a belt of 69,000 acres (280 km2) of forest reservations surrounding the city of Chicago. TheBrookfield Zoo (managed by the Chicago Zoological Society) and theChicago Botanic Garden (managed by the Chicago Horticultural Society) are located in the forest preserves.
Cook County is the fifth-largest employer in Chicago.[186]
In March 2008, the County Board increased thesales tax by one percent to 1.75 percent. This followed a quarter-cent increase inmass transit taxes. In Chicago, the rate increased to 10.25 percent, the steepest nominal rate of any major metropolitan area in America. InEvanston, sales tax reached 10 percent andOak Lawn residents pay 9.5 percent.[187] On July 22, 2008, the Cook County board voted against Cook County Commissioner's proposal to repeal the tax increase.[188]
In 2016, Cook County joined Chicago in adopting a $13 hourly minimum wage.[189] Cook County Board chairman John Daley called the wage hike "the moral and right thing to do." In June 2017, however, nearly 75home rule municipalities passed measures opting themselves out of the increase.[190]
Cook County has moreDemocratic Party members than any other Illinois county and it is one of the most Democratic counties in the United States.[191] Since 1932, the majority of its voters have only supported aRepublican candidate in a Presidential election three times, all during national Republican landslides–Dwight Eisenhower over native sonAdlai Stevenson II in 1952 and 1956, andRichard Nixon overGeorge McGovern in 1972. In 1984,Walter Mondale won Cook County with 51% of its vote despite losing in a landslide nationally toRonald Reagan. In 2020, 74 percent of the county voted forJoe Biden and 24 percent voted forDonald Trump.
In 1936, withFranklin D. Roosevelt receiving 1,253,164 votes in the county, Cook County became the first county in American history where a candidate received one million votes.
To establish more localized government control and policies which reflect the often different values and needs of large suburban sections of the sprawling county,secession movements have been made over the years which called for certain townships or municipalities to form their own independent counties.
In the late 1970s, a movement started which proposed a separation of six northwest suburban townships, Cook County'spanhandle (Barrington,Hanover,Palatine,Wheeling,Schaumburg, andElk Grove) from Cook to formLincoln County, in honor of the former U.S. president and Illinois resident.[195] It is likely thatArlington Heights would have been the county seat. This northwest suburban region of Cook was at the time moderatelyconservative and has a population over 500,000. Local legislators, led by State Senator Dave Regnar, went so far as to propose it as official legislation in theIllinois House. The legislation died, however, before coming to a vote.
In 2004,Blue Island mayor Donald E. Peloquin organized a coalition of fifty-five south and southwest suburban municipalities to form a new county, also proposing the nameLincoln County. The county would include everything south ofBurbank, stretching as far west asOrland Park, as far east asCalumet City, and as far south asMatteson, covering an expansive area with a population of over one million residents. Peloquin argued that the south suburbs are often shunned by the city (although Chicago is not bound or required to do anything for other municipalities) and he blamed the Chicago-centric policies of Cook County for failing to jumpstart the somewhat-depressed south suburban local economy. Pending sufficient interest from local communities, Peloquin planned a petition drive to place a question regarding the secession on the general election ballot, but the idea was not met with success.[196]
In arguing against the Lincoln County proposal, others noted several of the cities involved had power structures, law enforcement, orde facto "mayors for life" often accused in the press, or civilly or criminally charged with,political corruption,cronyism, andnepotism, and themselves being the main factor in their depressed economies rather than anyone in Cook County government. The opposition decried that their true reason for joining the secession effort was to start with a 'clean slate' with a new county government by design less willing to enforce responsibility against their abuses of power.[197][198]
Talk of secession from Cook County amongst some outlying communities again heated up in mid-2008 in response to a highly controversial 1% sales tax hike which has pushed the tax rates across the county communities up amongst the highest in the nation. Some border towns in particular had been outraged, as people can take their business across the county border (paying, for instance, 7% in Lake County instead of Palatine's 9.5%).[199] The secession issue eventually died down from the nominal tax increase.
In 2011, two downstate Republican state representatives,Bill Mitchell of the 87th district andAdam Brown of the 101st district, proposed statehood for Cook County. Mitchell said that Chicago is "dictating its views" to the rest of the state and Brown added that Chicago "overshadows" the rest of Illinois.[200]
Construction of theErie Canal in New York State made a connection from the Atlantic Ocean to the Great Lakes in 1821. As the Midwest farms proved productive, with much grain to sell to other parts of the US, Chicago and Cook County saw the benefit of a canal to improve the link from the Great Lakes to the Mississippi River. TheIllinois and Michigan Canal was completed in 1848, extending from the Bridgeport neighborhood in Chicago on the Chicago River, to theIllinois River at the cities of LaSalle-Peru. This canal spurred the growth of Chicago and the areas around it, as water travel was the primary way to ship grain or other commodities in that part of the 19th century. The Illinois and Michigan Canal ceased major operation in 1933. Portions are now designated as a National Historic Corridor. The two canals and the Great Lakes cemented trade ties between the Midwest and the Northeast, encouraging farmers to grow more than they needed to feed themselves in Illinois, with a large market for grain now open to them. Towns in Cook County along the Canal grew. From a national perspective, the trade ties made the South region of the US less important to the Northeast as a trade partner.
TheChicago Sanitary and Ship Canal, completed in 1900, largely replaced the functions of the Illinois and Michigan Canal. This canal resulted in the reversal of the direction of flow of the main stem and the South branch of the Chicago River; they used to empty into Lake Michigan and now those river sections flow toward theDes Plaines River. The Sanitary and Ship Canal was built to serve many aims, including ending using Lake Michigan as a sewer, sending waste water through treatment plants and sending it away from Lake Michigan. It is also a waterway for movement of ships.
The next major technology for transportation was railroads. Chicago and the towns along the canal and rivers understood the value of being a hub of a major network. Rail lines spurred out from Chicago by the 1850s, with major growth in the rail network for freight and passenger transportation coming after theAmerican Civil War, when the transcontinental railroads were completed, coast to coast across the US, stopping in Chicago, the heart of Cook County.
Following on the well-established position of Chicago as a transportation hub, the Interstate highway network maintained Chicago as a hub of that network, as well as serving the travel needs within the region.
When the age of air travel began in the 20th century,Midway Airport was built on 1 square mile (2.6 km2) of land and served as the major Chicago area airport from 1927 to 1955. Midway has been enlarged and continues to operate as of 2024[update]. As air travel became more important for passenger travel, and then for select freight commodities,O'Hare International Airport was built adjacent to a military airfield in the northwest part of Cook County. The City of Chicago annexed the land for the airport, so that the city controls both airports serving a large area. During the second half of the 20th century, it was the world's busiest airport. The approach of Cook County and Chicago to air travel has been the same as the approach to canal, railroad and highway transportation, to serve as a major national hub.
There has been a long running plan for a third major airport to serve the south side of the city and the southern and southwestern suburbs, theProposed Chicago south suburban airport intended for Peotone, Illinois. The state of Illinois has been addressing this topic since 1986. Some land has been acquired, but there is not a functioning airport there, as of August 2020[update].
Chicago's eight former townships and annexed parts of others no longer have any governmental structure or responsibility since their annexations, but their names and boundaries are still used on property plats and by Cook County for tax assessment purposes. In 2014, Evanston Township was dissolved by voters and its functions were absorbed by the city of Evanston.[203]
^"Social Capital Variables Spreadsheet for 2014".PennState College of Agricultural Sciences, Northeast Regional Center for Rural Development. December 8, 2017.Archived from the original on December 31, 2019. RetrievedDecember 30, 2019.
^Alexander Kent; Thomas C. Frohlich; Sam Stebbins; Evan Comen; Michael B. Sauter."The most Democratic counties in each state".USA TODAY.Archived from the original on November 17, 2020. RetrievedNovember 15, 2020.
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