Cook County, Illinois
Cook County is the most populous county in the United States, state of Illinois, and it is the second-most populated county in the United States after Los Angeles County, California. It is located in the Chicago metropolitan area. Cook County is home to more than 40% of the state's population, according to the 2010 census. The population was 5,275,541 as of the year 2020. In addition to being the most populous city in Illinois and the third-most populated city in the United States, Chicago serves as the county seat of Cook County.
Cook County was established in 1831 and named for Daniel Pope Cook, a prominent Illinois politician who lived in the 1800s. It was only in 1839 that it was able to establish its current limits. The state of Illinois was home to the vast majority of the state's inhabitants throughout the first half of the twentieth century. Within a century, the county saw tremendous population expansion, growing from a trade post hamlet with a little more than 600 persons to a county with four million individuals, rivalling the population of Paris by the time of the Great Depression.
On a geographical scale, it is the sixth-largest county in Illinois in terms of land area and the second-largest in terms of total area. Lake County shares the state's Lake Michigan coastline with the city of Chicago. Cook County, with its lake area, has a total area of 1,635 square miles (4,234.6 km2), making it the biggest county in Illinois. The land area of the county is 945 square miles (2,447.5 km2), and the water area is 690 square miles (1,787.1 km2), accounting for 42.16 percent of the total area. Cook County has a mostly urban and heavily populated land use pattern. Beginning with the completion of the Illinois and Michigan Canal in 1848, the State of Illinois took use of Cook County's proximity to Lake Michigan and the Chicago Portage to further its economic interests. This assisted in transforming a thriving agricultural sector into a primary centre for the transportation of crops and other commodities, which benefited both the county and a large portion of the state's economy.
Cook County has a population that exceeds that of 28 individual states in the United States, as well as the combined populations of the seven smallest states in the country. It is a part of the Chicago–Naperville–Elgin, IL–IN–WI Metropolitan Statistical Area, and it is bordered by what are known as the five collar counties in Illinois, Indiana, and Wisconsin.