civilization in mesopotamia vs north america?

Egypt and Mesopotamia both developed along major river systems, yet a comparable civilization did not apparently develop in North America along the Mississippi River Valley. Why do you thin this did not occur? What necessary factors for the rise of civilization were missing? Or was it simply a matter of accident?

Umm, your teacher is on crack…..

A large and intricate civilisation existed on the Mississippi-the Mould Builder culture.

Ask your teacher how the Incas, Mayans and Aztecs developed advanced civilisations based around large cities when NONE of these meso and south American societies were based on a large river system.