While waiting for our experts to chime in, please check out the Native American trade section of our FAQ. Specific to your interests, check out this discussion of trade routes connecting North America and Mesoamerica, and this entry on trade from Mesoamerica to South America. I also highly recommend the comments in this thread discussing trade along the Pacific Coast, and this one on trade between the Southwest and Mesoamerica.

Follow up question: Do we know of any contact between any 'Amerindians' and groups like the Aztec? Were they known to each other at all?