More can definitely be said, but it's a mistake to think that the current southern border of the USA draws a line between 'advanced' culture, and its absence (by which I presume you mean cultures that had settled towns rather than anything else - cultures can be quite advanced culturally in various ways while still living hunter-gatherer lifestyles). Have a read of this older previous answer by /u/reedstilt which is a good introduction to North American settlements like Cahokia, and this one, which goes into more detail on Cahokia (and links to further posts with yet more info on specific events in the area). Additionally, a more recent answer by /u/400-Rabbits answering a similar question takes a different slant, discussing continuities and similarities between the cultures of modern-day Mexico and modern day USA.

Hey there,

Just to let you know, your question is fine, and we're letting it stand. However, you should be aware that questions framed as 'Why didn't X do Y' relatively often don't get an answer that meets our standards (in our experience as moderators). There are a few reasons for this. Firstly, it often can be difficult to prove the counterfactual: historians know much more about what happened than what might have happened. Secondly, 'why didn't X do Y' questions are sometimes phrased in an ahistorical way. It's worth remembering that people in the past couldn't see into the future, and they generally didn't have all the information we now have about their situations; things that look obvious now didn't necessarily look that way at the time.

If you end up not getting a response after a day or two, consider asking a new question focusing instead on why what happened did happen (rather than why what didn't happen didn't happen) - this kind of question is more likely to get a response in our experience. Hope this helps!