In South and Central America we have large, city building empires with complex system of governments. But in North America the majority of Natives (at least ones we learn about in school) appeared to remain tribal and nomadic. If you look at the geography of the regions things don’t make much sense. Large cities such as Cuzco and Tenochtitlan were built in heavily jungled areas. Not really a place you’d want to build a city. North America is arguably much better suited, geographically speaking, for building cities and road networks and courier systems. So why is it that a majority of Native built cities are located in Central and South America while there are almost none in North America?
North America in fact had Pre-Columbian urban sites, notably Cahokia, not too far from modern-day St. Louis.
u/Reedstilt has some answers, plus some additional useful background information by u/RioAbajo.
Also worth noting are the Pre-Columbian settlements in the modern-day American Southwest, notably Chaco Canyon and Mesa Verde. u/bix783 discusses the history of the cultures behind those settlements.
Finally via u/Reedstilt in another answer, while it varied quite a bit from people to people and region to region, overall it's erroneous to think of pre-Columbian North Americans as nomadic - much of what is now eastern North America and the Southwest engaged in agriculture.
I had no idea that there were so many urban sites in the mainland US. What about the geography is South America? How were the people there able to build such great cities if so much of the terrain was so mountainous and full of jungles? It seems like South America is really ill suited for large, urban centers. It’s really interesting.