[Lessismore]

Actually, Canada would be in a comparatively good position after an attack. With the cities and their populations gone, it would have a small, widely-dispersed rural population that would be fairly well equipped to survive as agriculturalists and hunter-gatherers. The US, on the other hand, would likely wind up with far too many survivors of the initial attack, and the ensuing disease, famine, organized crime, etc, would be comparatively worse.

[RadioAstronomer]

I concur completely!