Cook County, Illinois is the most populous county in the state. It is the second largest county in the United States, second to LA County, CA. About 40% of all Illinois residents live in Cook County. In 2020, the population was almost 5.3 million. Its county seat is Chicago, Illinois’s largest city and the third-largest in the United States.
History of Cook County, Illinois
Cook County was founded in 1831 with a population of around 600 people and grew to over 4 million residents a century later, rivaling Paris! Cook County, Illinois is the sixth largest county in terms of land area but the largest in terms of total area, with 42% of its total area covered by water. The county is home to nearly 130 municipalities. Cook County is comprised of 24 cities, one town, and 111 villages. Outside of Chicago and Evanston – Cook County’s only two self-contained cities – the county is divided into 29 townships.
Cook County is bounded by Chicago and the greater Chicago metropolitan area, collectively referred to as Chicagoland. Cook County, Illinois has a population that exceeds that of 28 US states! 75% of Illinois residents live in the Chicago metropolitan area, and 40% in Cook County alone.
County of Cook, Illinois Demographics
- Cook County has a population of 5,275,541 people.
- 945 square miles in size
- Density of population: 5,450 inhabitants per square mile
- Age median: 37.2
- The median household income in Cook County is $64,660.
- The median home price in Cook County is $285,000
- Educational attainment: 88 percent have completed high school or have earned a GED; 41 percent have earned a bachelor’s degree or higher.
Cook County Cities Frequently Asked Questions
How many cities in Cook County, Illinois?
Cook County is comprised of 24 cities, one town, and 111 villages. Each of the three municipalities is incorporated and has the same legal authority.
Which city in Cook County is the most populous?
Chicago is Cook County’s largest city, with 2.74 million residents out of the county’s total population of 5.27 million.
What Chicago suburbs are in Cook County?
Cook County includes some of Chicago’s most affluent suburbs, including Evanston, Elgin, Cicero, Arlington Heights, Schaumburg, Palatine, Skokie, Des Plaines, Orland Park, Berwyn, Park Ridge, and Buffalo Grove (shared with Lake County).
Which cities in Cook County are the wealthiest?
The following list shows the wealthiest cities in Cook County in terms of median household income.
- $102,628 Arlington Heights
- $90,345 Orland Park
- $87,156 Schaumburg $83,834 Palatine
- 81,543 dollars in Evanston
Cook County, Illinois is located in the state of Illinois. It is located on the shores of Lake Michigan in northeastern Illinois. It is bounded by the Chicago metro area’s five “collar counties”: DuPage, Kane, Lake, McHenry, and Will.
Cook County shares a coastline with Lake Michigan, one of the world’s largest freshwater lakes. While the majority of Cook County’s land is developed, the county does have a robust forest preserve system, with over 70,000 acres dedicated to natural areas such as woodlands, marshes, prairies, and hundreds of miles of trails.
Cook County is comprised of over 800 local governmental units and nearly 130 municipalities, the largest of which is Chicago, which is home to approximately 54% of the county’s population. Outside of the city limits of Chicago and Evanston, the county is divided into 29 townships, which frequently share or divide governmental services with local municipalities. Townships within the city of Chicago were abolished in 1902 but retained for the purpose of real estate assessment. Formerly contiguous with the City of Evanston, Evanston Township was dissolved in 2014. The Cook County Board oversees county government, and state government offices located throughout the county include the Circuit Court of Cook County, the Cook County State’s Attorney, the Cook County Sheriff, and the Cook County Assessor.
Geographically, the county ranks sixth in Illinois in terms of land area and first in terms of total area. It is adjacent to Lake County on the state’s Lake Michigan shoreline. Cook County, including its lake area, has a total area of 1,635 square miles (4,234.6 km2), making it the largest county in Illinois, with a land area of 945 square miles (2,447.5 km2) and a water area of 690 square miles (1,787.1 km2) (42.16 percent). Cook County’s land use is primarily urban and densely populated. The State of Illinois capitalized on Cook County’s proximity to Lake Michigan and the Chicago Portage, beginning with the construction of the Illinois and Michigan Canal in 1848. This contributed to the region’s status as a national transit hub.
Cook County’s population is greater than the combined populations of the 28 smallest states in the United States and the seven smallest states individually. It is part of the Chicago–Naperville–Elgin, IL–IN–WI Metropolitan Statistical Area and is surrounded by the five collar counties.