Cook County is a county in the American state of Illinois. Chicago is the county seat of Cook County. Los Angeles County, California is the only county with a higher population than Cook County.
About 5,231,000 people live in Cook County. This is 40.6 percent of all the people who live in Illinois. Cook County's population is more than the population of 29 U.S. states. More people live in Cook County than in the seven smallest U.S. states combined. There is a tax on canned beverages in Cook County.