Chicago River

The Chicago River is the iconic waterway running right through downtown Chicago, one of the city’s most recognizable landmarks. Originally, the river flowed naturally into Lake Michigan, carrying the rapidly growing industrial city’s sewage straight into the lake — which also happened to be Chicago’s main source of drinking water. This caused devastating outbreaks of cholera and typhoid fever.To solve this life-threatening pollution crisis, Chicago’s engineers accomplished one of the most audacious civil engineering feats in history between 1889 and 1900: the complete reversal of the river’s flow (the famous Chicago River Reversal). By constructing the Chicago Sanitary and Ship Canal, together with locks, pumping stations, and an engineered slope, they literally turned the river around. Since January 2, 1900, the Chicago River has flowed away from Lake Michigan — westward through the city from the lake, then southwest into the canal system, eventually joining the Mississippi River watershed.Today, the Chicago River stands as a powerful symbol of human ingenuity, urban renewal, and environmental problem-solving. It hosts boat tours, famously turns bright green every St. Patrick’s Day, and has transformed from a polluted “stinking river” into a vibrant recreational and economic asset — and yes, it still flows backwards.