There is an easy resolution to this problem.
Simply annex all of Canada, with the exception of Quebec (which would be allowed to declare sovereignity), then admit each of the provinces individually as states.
Then annex all of Mexico, admitting each each of their states on an individual basis as well, as soon as they have achieved a basic competence in English for the majority of their citizens, and the legal code is reformed so it comforms with, or at least eliminates the parts that conflict with, common law in the United States.
Now, stop bothering us about that. We got a global war to fight.
Quebec could be treated the same as Texas. They can join provisionally. If they don't like it, then they can leave the union...........
That's a perfect idea.
(sarcasm)
Why would we annex parts of a country with a per capita GDP of less than $7,000? Don't we waste enough money as it is?
'Simply annex all of Canada, with the exception of Quebec (which would be allowed to declare sovereignity), then admit each of the provinces individually as states.'
I think you'd have to ask Elizabeth II as she still owns Canada. Anyways, remember what happened last time we tried to 'annex' Canada - we lost! :)