Chicago River

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 (the Chicago Loop). The river 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. In 1887, the Illinois General Assembly decided to reverse the flow of the Chicago River through civil engineering by taking water from Lake Michigan and discharging it into the Mississippi River watershed, partly in response to concerns created by an extreme weather event in 1885 that threatened the city's water supply.