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What caused residents to abandon the ancient settlement that made the area near Cahokia, Illinois, home to the biggest city in the Western world? At its peak approximately 1,000 years ago, the settlement was bigger than London. But by A.D. 1400, it was virtually deserted.
Cahokia’s collapse has long been a subject of speculation. For several decades, one of the most persistent theories has blamed self-inflicted ecological disaster. First suggested by researchers at Southern Illinois University-Edwardsville in 1993, the theory held that the Mississippians who inhabited the city cut down forests in the nearby uplands, leading to erosion and flooding.
But the evidence underlying the theory was negligible, said geoarchaeologist Caitlin Rankin. The researchers knew that the people living in the area used wood, and that “there was increasing use of upland trees, happening more towards the end of Cahokia’s occupation,” she explained on Tuesday’s St. Louis on the Air.