Cook County residents are proud of their heritage and history. The county contained much of what is now Lake, DuPage, Will, McHenry, and Will counties formed in 1831 with around 100 inhabitants in 2,464 square miles. It was Illinois' 54th county, named after Daniel Cook, one of its early and most youthful politicians. Cook County lost approximately half of its territory in the 1830s due to population development in northeastern Illinois but continued to expand. By 1839, it had grown to 954 square miles and had established its present uneven borders. In addition, it had grown to a population of over 4,000 people.

During the 1830s and 1840s, farmers bought up most of the county's accessible land and began cultivating crops and cattle. Because there were no railways, some farmers transported their produce to Chicago, while others traveled to smaller towns closer to home. As a result, Wheeling, Gross Point (now Wilmette), Lyons, Summit, Brighton, Willow Springs, Calumet, Blue Island, and Thornton were flourishing towns by 1840.

Most of the county's remaining farmland was developed in the 1970s and 1980s. Contiguous urban expansion had swallowed both the residual farms and the suburban residential and industrial zones that had previously been separate from the city core by that time.

Daniel Pope Cook was a politician, lawyer, and newspaper proprietor from Illinois. He was the first attorney general to serve the state and subsequently a legislator, and he was an anti-slavery activist. In 1794, he was born into a poor branch of the renowned Pope family of Kentucky and Virginia in Scott County, Kentucky. In 1815, Cook relocated to Kaskaskia, Illinois, and accepted a job as a store clerk, but he soon began studying law under his uncle, Nathaniel Pope. Later, he was called to the bar and began practicing in Kaskaskia. On October 16, 1827, Daniel Pope Coke died in Scott County, Kentucky.