Pretty much the title, but did they have any idea about one another? Geographically they’re not that close and I am unsure if either migrated that far north or south. To further add why was there such a big differentiation in culture? The Natives of the North are often seen as nomadic tribesmen, whereas the south they had grand cities and civilizations. Is there any known reason for either?
For your last question, this FAQ answer by u/RioAbajo will give you a good sense of some of the difficulties in answering why one thing or another didn't happen in North America.
You might be interested in /u/reedstilt's and /u/RioAbajo's earlier descriptions of the North American city of Cahokia, which was home to 40,000 people and was built on a series of earthen pyramids pretty near where St. Louis stands today.