On January 2, 1900, Chicago broke a dam at dawn, and the river started flowing away from Lake Michigan. The city kept it quiet because Missouri was getting ready to sue. St. Louis filed about two weeks later, and the U.S. Supreme Court eventually ruled for Illinois.
The canal that carries the river is 28 miles long, and digging it moved about 42 million cubic yards of earth. Isham Randolph was the chief engineer.
Every so often the river runs backward again. In a big enough storm the locks open to the lake, as they did in April 2013 and again in October 2017, when they stayed open about 19 hours.