Chicago is the largest city in Illinois and the seat of Cook County. Situated on the southwestern shore of Lake Michigan, Chicago is a global city and serves as the center of culture, politics, industry, transportation, medicine, and higher education for the Midwest. Chicago's vast metropolitan area (the third largest in the U.S.) is known informally as "Chicagoland" and encompasses ten separate counties, including two in Indiana and one in Wisconsin.

The area was originally inhabited by several Native American tribes, who named the land Checagou. The meaning of "Checagou" is still a matter of debate; some say it was an honorific meaning "strong" or "great" while others claim it meant "wild onion" or "skunk," as the marshlands at the time were ripe with the smell of rotting leeks. In the 1770s, Jean Baptiste Point du Sable, the child of a Haitian slave and a French pirate, built a trading post at the mouth of the Chicago River. Known to the natives as "Black Chief," Du Sable became a prominent member of the Potawatomi tribe.