Well, it's in the political section, so short of actually threatening someone, it's wide open.
Let me start things rolling (maybe) by repeating what I said in the connecticut thread. Canada's last mass killing (other than gang stuff) that I can remember is the Montreal Massacre in Dec 89. I asked my wife cold what's the last one she remembered and she said the same.
Even allowing for the dfferences in population (which I'm not sure is even relevant), that's a huge difference. So WHY the difference? Is Canada unusually low or is the U.S. abnormally high?
It's tempting to go with the cliches and say it's the gun culture in thr US or that Canadians are very polite. Both may be true, but is it enough to explain it?