Not meant to be passive-aggressive, it's just that the place is nearly impossible to map like the rest of the world is mapped.
It what was said about medieval Africa, tough, and it was essentially better of a situation.
As for what matter North America, the main problem is that we don't have litterary sources up to the XVth. Oral sources and Archeological sources tough, are a thing.
Even without going into detail about relevance of Alden or Renfrew-Level models (which can be another discussion altogether), there is enough clues about cultural limits that can be used for mapping.
Of course it's more or less vague, but it can provide much informations (and to be honest, half of ancient and medieval borders in Europe are approximations, in spite of litterary evidence : you don't have clear borders in these region before the XVIth century) and is not really a carthographic Terra Incognita.
My bad, reading various years in the discussion about France may have got me turned around.
J.Gouw maps are usually quite distorted, and it's why I never used it at least conciouslly, because I don't really trust enough his work. Maybe I should have looked on other revisions, but
The basemap I use (I didn't corrected the rivers I modified on it, tough) is
this one.
Most of the changes appears to be located in Canada or artificial lakes (which plays little role on maps, and that I try to get rid of) and maybe some rivers. It should maybe be used more, but differences are quite reduced at the point it should warrant more of a patch from
this map than a change IMO. (Admittedly, I should put the rivers changes and additions I did)
But really, people should just update the wiki more : nobody wants to dig in a thread in search of a basemap.