The city’s problems were not unique. Cahokia’s rise coincided with the spread of maize throughout the eastern half of the United States. The Indians who adopted it were setting aside millennia of tradition in favor of a new technology. In the past, they had shaped the landscape mainly with fire; the ax came out only for garden plots of marshelder and little barley. As maize swept in, Indians burned and cleared thousands of acres of land, mainly in river valleys. As in Cahokia, floods and mudslides rewarded them.
