900 Years Ago, One of the Largest Civilizations in the World Was Abandoned New Clues

The Cahokia Mounds, once a thriving settlement near present-day St. Louis, was abandoned by 1400, leaving behind a mystery. Recent research challenges the long-held belief of drought-induced crop failure as the cause. Instead, evidence suggests the Cahokians may have had the skills to mitigate such environmental challenges, and their departure was likely influenced by social factors and external pressures.

Nine hundred years ago, the Cahokia Mounds settlement, located just across the Mississippi River from what is now St. Louis, was a thriving metropolitan area with a population of around 50,000. It was one of the largest communities in the world at the time. However, by 1400, this once-bustling site had become nearly deserted, and the reasons for the mass departure remain a mystery.

One popular theory is that the Cahokia residents abandoned the settlement after a massive crop failure brought on by a prolonged drought. But a new study in the journal The Holocene by Natalie Mueller, assistant professor of archaeology in Arts & Sciences at Washington University in St. Louis, and Caitlin Rankin, PhD ’20, suggests the Cahokians likely had other reasons to leave town.