content: That's obvious.  The problem for America is that invading Canada would mean war with the rest of the world.  It wouldn't necessarily be war against the US but for control of Canadian (and American... Alaska/Hawaii) resources.  Any country would have difficulty defending 4 sides.  Anyways, Canada/USA are nowhere close to war and I pray it never happens.  We both have it pretty good and I want to keep it that way.