Mammoth Spring

Historical marker location:

1909 Spring Road, Oak Brook, Illinois

( Marker can be reached from Spring Road, on the right when traveling north.)

Illinois was part of the French colonial empire, and the city of Cahokia, located near present-day Collinsville, was one of the largest pre-Columbian cities in North America. At its peak, around 1250 CE, Cahokia had a population of around 20,000 people.