Layout of Cahokia on the west bank of the Mississippi River.
Bit by bit, more information is being discovered related to the massive Native American mound settlement called Cahokia in western Illinois.
According to an article in Science:
A millennium ago, this strategic spot along the Mississippi River was an affluent neighborhood of Native Americans, set amid the largest concentration of people and monumental architecture north of what is now Mexico.
Back then, hundreds of well-thatched rectangular houses, carefully aligned along the cardinal directions, stood here, overshadowed by dozens of enormous earthen mounds flanked by large ceremonial plazas. … Cahokia proper was the only pre-Columbian city north of the Rio Grande, and it was large even by European and Mesoamerican standards of the day, drawing immigrants from hundreds of kilometers around to live, work, and participate in mass ceremonies.
Recent excavations have uncovered evidence of more than 500 thatched houses and workshops where residents created goods. Cahokia may have expanded out into a primitive metropolitan area that served as residence to tens of thousands of Native Americans, researchers believe.