Chicago Canal

The Chicago Sanitary and Ship Canal, historically known as the Chicago Drainage Canal, is a 28-mile-long (45 km) canal system that connects the Chicago River to the Des Plaines River. It reverses the direction of the Main Stem and the South Branch of the Chicago River, which now flows out of Lake Michigan rather than into it. The related Calumet-Saganashkee Channel does the same for the Calumet River a short distance to the south, joining the Chicago canal about half way along its route to the Des Plaines. The two provide the only navigation for ships between the Great Lakes Waterway and the Mississippi River system.

The canal was primarily built as a sewage treatment scheme. Prior to its opening in 1900, sewage from the city of Chicago was dumped into the Chicago River and flowed into Lake Michigan. The city's drinking water supply was located offshore, and there were fears that the sewage could reach the intake and cause serious disease outbreaks. Since the sewer systems were already flowing into the river, the decision was made to dam the river and reverse its flow, thereby sending all the sewage inland where it could be treated before emptying it into the Des Plaines.

A secondary goal was to replace the earlier Illinois and Michigan Canal (I&M), which had originally connected Lake Michigan with the Mississippi starting in 1848, but had been unsuccessful in its attempt to widen its course. As part of the construction of the new canal, the entire route was built to allow much larger ships to navigate it. It is 202 feet (62 m) wide and 24 feet (7.3 m) deep, over three times the size of the I&M. The I&M became a secondary route with the new canal's opening, and was shut down entirely with the creation of the Illinois Waterway network in 1933.

The canal is operated by the Metropolitan Water Reclamation District of Greater Chicago. In 1999, the system was named a Civil Engineering Monument of the Millennium by the American Society of Civil Engineers (ASCE). The Canal was listed on the National Register of Historic Places on December 20, 2011.

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