Chicago Reversed Its Own River to Solve a Sewage Crisis

In 1900, Chicago made permanent something it had only managed partially and briefly before: it reversed the flow of an entire river. The Chicago River had historically drained into Lake Michigan — the same lake that supplied the city's drinking water. By the late 1800s, untreated sewage flowing into the lake was causing regular typhoid and cholera outbreaks. The city's solution was audacious: build a 28-mile canal to reverse the river's flow so it drained away from the lake instead. An earlier attempt in 1871, deepening the Illinois & Michigan Canal, had only partly and temporarily turned the current. The Chicago Sanitary and Ship Canal opened on January 2, 1900, and the river's flow was reversed permanently. Downstream states immediately sued, arguing Chicago was simply moving its sewage problem to their rivers. The legal battles lasted decades. The reversal remains one of the largest public works projects in American history, and it worked: typhoid deaths in Chicago fell sharply in the years that followed, helped along by later changes such as water chlorination. The river now flows backwards from the way nature intended, permanently.