Chicago is the largest city in the state American State of Illinois. Currently the city has grossed over 2.8 million residents by the last official consciences. Chicago has been also been declared as the most populated city in the Midwestern area of United States and it has the honor of being the third most populated city in the whole country of united states. Its famous metropolitan area is commonly termed as "Chicagoland," and has been declared as the 26th most populous commercial areas in the world, home to an estimated 9.7 million people spread across the U.S. states of Illinois, Wisconsin, and Indiana. Chicago is the county seat of Cook County.