Chicago is the most populous city in the state of Illinois in the United States. It is the seat of Cook County, the second most populous county in the United States after Los Angeles County, California. It owns less than 1% of its territory in DuPage County.
It is the fifth most densely populated locality in Illinois. Its metropolitan area, commonly known as "Greater Chicago", is the 27th most populous urban agglomeration in the world, home to more than 9.6 million people spread across the US states of Illinois, Indiana and Wisconsin. Just over 21% of the total population of Illinois lives in Chicago.
Founded in 1833 near a berth between the Great Lakes and the Mississippi River basin. With more than 2.7 million inhabitants, according to the 2020 census it is the most populous city in the Midwest region and the third most populous in the United States, after New York and Los Angeles.
