ILLINOIS: The catalyst behind the pre-Columbian city of Cahokia’s rapid rise may have been the arrival of maize cultivation technology. Isotope analysis of human and dog teeth found there provided insight into the local diet, and dating of corn kernels from the Mississippi River site reveal that maize was abruptly introduced to the area between A.D. 950 and 1000. This development likely helped fuel Cahokia’s population explosion over the next century, at the end of which it had as many as 20,000 inhabitants, making it the largest settlement in North America.