Northbrook is a suburb of Chicago, located at the northern edge of Cook County, Illinois, United States, on the border of Lake County. Per the 2020 census, the population was 35,222.

The Chicago River is a system of rivers and canals with a combined length of 156 miles (251 km) that runs through the city of Chicago, including its center. Though not especially long, the river is notable because it is one of the reasons for Chicago's geographic importance: the related Chicago Portage is a link between the Great Lakes and the Mississippi River Basin, and ultimately the Gulf of Mexico.