Cook County was first created in 1831. It used to cover a larger area, spanning into what are now the McHenry, Will, and DuPage counties, but found its present size in 1839.

The Chicago region has a history as home and traveled region for a number of indigenous peoples, especially because of the bodies of water nearby. The Chicago government website has a list of tribes who had a presence in the area before European settlement, including Hoocąk, Kiikaapoi, Inoka, and many other nations; you’ll find the full list on the City of Chicago’s website.

Chicago’s history as a city pre-dates Cook County itself. Jean Baptiste Pointe du Sable, a trader who many believe was born in Haiti, is considered the the first non-indiginous settler in what is now Chicago. Along with his wife, a Potawatomi woman named Kitihawa Point Du Sable, he set up a farm and trading post along the Chicago River in the 1780s; this settlement eventually grew to become the city of Chicago.

Fort Dearborn was built in 1803 and was the site of the Battle of Fort Dearborn, or the Fort Dearborn Massacre, during the War of 1812. It was burned down following the battle. In 1816, a new fort was built in the same spot. Though the fort was later decommissioned, you can still visit the historical site; markers and a monument commemorate its location in downtown Chicago off the bustling Michigan Avenue, not far from a bust of Jean Baptiste Pointe du Sable.

In 1837, the settlement officially incorporated as the City of Chicago. It was a major transportation hub thanks to the Illinois & Michigan Canal (finished in 1848), and then due to railroads.

The Great Chicago Fire of 1871 destroyed much of the city, but also paved the way for it to grow; the debris was piled into the lake, creating new space to build on, and the city grew again. The Great Chicago Fire also accelerated the growth of Chicago’s suburbs as people whose homes had been destroyed moved to outlying areas due to the destruction. That includes Elgin, which is the second-largest city in Cook County.

Cook County is named for Daniel Pope Cook. Cook accomplished a great deal in his short life: though he died at just 33 years old, he was the first attorney general of Illinois and its second U.S. Representative. That’s in addition to careers in law and newspaper publishing.

Noted for his vehement opposition to slavery, Cook’s political career included helping defeat a proposed convention to make slavery legal within Illinois. His family continued his abolitionist values: his son would go on to become the mayor of Springfield, which is the Illinois state capitol, as well as to fight for the Union in the Civil War.