Cahokia, The City That Vanished

A thousand years ago, on the American Bottom floodplain just east of where the Missouri meets the Mississippi, a city rose. It was not a village or a ceremonial camp. It was a metropolis. At its peak, around the year eleven hundred, Cahokia held somewhere between ten thousand and twenty thousand people, making it larger than London at the same moment in history. Archaeologists call it the largest pre-Columbian city north of Mexico. Its inhabitants built more than one hundred and twenty earthen mounds, some of them aligned with the solstices. The central mound, today called Monks Mound, covers fourteen acres at its base and rises one hundred feet above the plain. It remains the largest prehistoric earthwork in North America.

The people who built Cahokia were part of the Mississippian culture, a network of chiefdoms that spread from the Gulf Coast to the Great Lakes. Their city was a religious and political center, a place of ceremony and commerce. Cedar posts arranged in circles, which archaeologists have nicknamed Woodhenge, appear to have tracked the movements of the sun. Copper and shells from the Gulf of Mexico have been found in the mounds, evidence of trade reaching hundreds of miles in every direction.

By the thirteen fifties, Cahokia was abandoned. No one knows exactly why. Climate change, drought, soil exhaustion, political fragmentation, epidemic, flooding, or some combination of all of these have been proposed. What we do know is that when French explorers arrived in the sixteen hundreds, the city was gone. The mounds remained, overgrown and quiet, and would remain so for centuries before anyone understood what they were looking at.

Today the Cahokia Mounds State Historic Site in Collinsville, Illinois, is a UNESCO World Heritage Site. The soil beneath these mounds still holds an astonishing record of a civilization that once organized the continent.