Mike117 perhaps the US Consulate in Ottawa Canada's website will give you insight into regulations regarding bringing firearms into Canada. In no case will you be issued an Authorization to Transport a "Restricted Firearm" for the purpose of hunting or self protection. (see restricted weapons)
Many American hunters bring rifles and shotguns into Canada, as do those attending shooting competitions, but please do not get caught with one that you have not declared.
http://canada.usembassy.gov/travelin...to-canada.html
levi: To answer the question in your original post, I do not consider the possibility of those events happening when I am deciding where I travel in North America and refuse to be controlled by the cloud of fear under which the terrorists would have us live our day to day lives.
I echo the comments with respect to our Police Forces and Intelligence Agencies, they are doing a great job with few exceptions.