A bit difficult for the US to make a claim, as it was based pretty much solely on the earlier French claims for the whole Mississippi basin, despite the French having only ever seen the smallest portion of it. Seems likely the U.S. would decide to just claim up to the Lake of the Forests, with the added bonus of including most of the 'unclaimed' area as well. Back then that land was claimed by the Hudson Bay Company anyways, though it might make no difference to the British. How is recognition handled here? Is the land occupied by the U.S.,while maps almost always show it as being British, as they do with the Sudan situation? I also feel that in a situation like this the Red River areas are going to have plenty of Lakotah, Dakota, Metis, so-on and so-forth there. Something with an independent Manitoba around would be interesting... Still, there is a rather narrow window of opportunity for this, with the U.S. having settled its border with Spain (and the Soanish dealing with both Anglophinic countries to decide on the southern border of the Pacific Northwest) and Mexico going independent within less than a decade (I think).