What if the Vikings did a serious expansion into the Americas? I mean with forts and real settlements?

What I'm trying to look at is what the world would have been like, imagine such an earlier time period that the European technology and government systems could have been adopted by the Native Americans. Diseases could have slowly spread into the Americas but I'd imagine it would have been slow enought that they would have built their immune systems to them.

Ideally in my picture the link between North America and Europe would have stayed open via my permanent Viking settlements in the North. I'd imagine a major expansion of trade in Canada and New England. Also the flow of information would have allowed the North Americans to benefit from new technological developements (gunpowder) as they became more common instead of being thrown against them suddenly. Also horses and farming technology would most likely have been brought over earlier as well allowing the Native Americans to adopt them earlier. Also Europe would have had trade from the Americas as well so we might have seen corn, cocoa, and other items appear in Europe much earlier.

I like to imagine that some Native Americans would have made small Kingdoms of the European type and had true fortifications. The Central American Empires wouldn't have been wiped out by disease and would probably built up small trading fleets to trade with modern day Canada which would in turn trade with Europe and vise versa.

It think that American History would have been a lot more intersiting (for me at least) if this had happened. Not to mention that a lot of the older American History that had already happened would have been given a greater chance to have been written down and preserved for the future instead of just having to guess what was happening during pre Columbus America.