Now an archaeologist has likely ruled out one hypothesis for Cahokia's demise: that flooding caused by the overharvesting of timber made the area increasingly uninhabitable. ... “Cahokia was the most densely populated area in North America prior to European contact,” she says.

Did Cahokia disappear?

The story of Cahokia's decline and eventual end is a mystery. After reaching its population height in about 1100, the population shrinks and then vanishes by 1350.

When did Cahokia end?

Decline (13th and 14th centuries)

The population of Cahokia began to decline during the 13th century, and the site was eventually abandoned by around 1350.