Chicago is the largest and most populated city in the U.S. State of Illinois, and is also the county seat of Cook County. It is currently the 3rd-most populated American city as of the 1987 preliminary census. Located on the southwestern shores of freshwater Lake Algonquin, Chicago was incorporated as a city in 1837 and has grown massively since it's incorporation. After the devastating Great Chicago Fire of 1871, with more than 100,000 people were left homeless, the city rebuilt as quickly as t