What allowed Native Americans in Mexico to settle cities larger than those in areas to the north?

Answer;

The use of farming to feed a larger population;

The use of farming to feed a larger population allowed the Native Americans in Mexico to settle cities larger than those in areas to the North.

Explanation;

The use of farming to feed a larger population caused Native Americans in Mexico to settle their cities larger than those in in areas to the North. This paved the way for many advancements in Agriculture for the Native Americans which made them an interesting target for colonizers.

One of the main factors that allowed Native Americans in Mexico to settle cities larger than those in areas to the north was that Central America contained far more gold and riches that acted as currency and boosted the economy. Practically no gold was found in what is now the eastern United States.