My two cents.
I'm an American and proud to be an American. I'm also proud to say that I have very, VERY good friends who live in Canada, particularly in Toronto, Montreal, and Calgary. I visit frequently (but hobby rarely) and I've never been shown anything but graciousness and courtesy (except for a few times in Quebec City, but that's a story for another day).
I live and work 3 miles from the World Trade Center and on that terrible day in 2001, and in the days that followed, ALL my friends from Canada either contacted me or attempted to contact me. They told me tales of the horror they, their friends and family went through watching the events unfold. In other words they felt a HUMAN CONNECTION with the dead and suffering.
Sure it's fun to poke at each other. Hockey, baseball, beer, politics, etc., etc. But when it comes down to it, we share a common culture and language (more or less). Our historys are intertwined and, in many ways, inseparable.
One last thing, I know of a man from Ontario, a volunteer Emergency Medical Technician, who was a few blocks away from the Trade Center on his way to a business meeting (computers maybe?) when the planes hit. On instinct he went to the aid of the injured and dying. He was never seen again.