Final answer:
Native American civilization was least highly developed in North America compared to more advanced societies in Mexico, Central America, and Peru.
Step-by-step explanation:
The civilization that was least highly developed in terms of organized social structures and population size was that of Native Americans in North America. While civilizations in Mexico, Central America, and Peru developed advanced societies with complex social structures, extended trade routes, and significant agricultural advancements, North American Native cultures were more dispersed and did not have the same level of population or organization. Societies such as the Mayan, Aztec, and Incan had impressive cities, temples, and infrastructures, whereas the Native American cultures in North America were less centralized and often focused on hunting, gathering, and small-scale agriculture.