Which Great Lake is connected to the Mississippi River basin by the Chicago River?

Lake Michigan is connected to the Mississippi River basin by the Chicago River.

The Chicago River originally flowed into Lake Michigan, but nineteenth-century engineers reversed its direction. The Chicago Sanitary and Ship Canal, completed in 1900, redirected water away from the lake and toward the Des Plaines River. That river joins the Illinois River, which flows into the Mississippi River.

The project was built chiefly to carry Chicago’s sewage away from Lake Michigan, the city’s drinking-water source. It created a hydrological connection between the Great Lakes and the Mississippi basin, although locks and other controls regulate the system. The Chicago River itself is now famous for its annual green dyeing on St. Patrick’s Day.

This connection does not mean that Lake Michigan naturally drains into the Mississippi. The Great Lakes’ principal eastward outlet remains the Saint Lawrence River, and the Chicago diversion is a human-engineered link with a relatively small flow compared with the lake’s total volume.