what would have made travel across north america difficult for early americans

Answer 1

It depends on what you are classifying as early Americans. If you are referring to earlier settlers from Europe, I think the terrain proved to difficult, as they couldn't navigate the mountains and streams effectively, with their belongings. If you are referring to Native Americans, I think it was a matter not psychically able to do it, as they did not get horses until the European arrived.

Answer 2

Thousands of years ago, during the last Ice Age, the early Americans (aka Paleo-Indians) found it difficult to travel across North America because the vast ice sheets, the Laurentide and Cordilleran, blocked most of what is now Canada. As a result, only a handful of the early Americans traveled across North America. However, there is a theory that the early Americans came much earlier than expected by traveling along the coastlines of North America.

I hope this helps.