@evan I mean, I dig your enthusiasm and forward thinking, but...
Many American states in the north near the border wouldn't probably be too bothered by becoming Canada. You're unlikely to encounter resistance in say Maine or Minnesota.
But your problem comes in considering this as a land war action. The US wouldn't move infantry in until after Shock and Awe...that's been their strategy for the last 3 engagements.
Also, Donald has fired all of the actual War College generals. There is nobody in charge of the US military who understands tactics. These are small, stupid men. And you know what happens if you back small stupid men into a corner? They do crazy shit.
Do you have faith that Donald's army wouldn't launch tactical bomb busters, white phosphorus and chemical weapons into Toronto just like they did in the Middle East?
Palestine was a test run to see what "democracies" could get away with when it comes to mass destruction. It's a lot.