chicago | ispartof | dupage_county_illinois <sep> chicago ( (listen) shih-kah-goh, locally also  shih-kaw-goh; miami-illinois: shikaakwa; ojibwe: zhigaagong) is the most populous city in the us state of illinois and the third-most populous in the united states after new york city and los angeles with a population of 2,746,388 in the 2020 census, it is also the most populous city in the midwest as the seat of cook county (the second-most populous us county), the city is the center of the chicago metropolitan area, one of the largest in the world 
chicago is part of dupage county in illinois.chicago is the most populous city in the u.s. state of illinois and the third-most populous in the united states