While certain inner-city venues in the U.S. tend to generate the majority of crime statistics, it's still considered safe to travel throughout the U.S. and Canada. But, as far as travel safety is concerned, Mexico can never be called the "same" as it's northern neighbors.
Citing United Nations figures for murder rates for the the past 5 years we find, per 100,000 peeps:
Canada: 2006 = 1.6 2011 = 1.6 = No change
United States: 2006 = 5.7 2011 = 4.7 = 21% Decrease
Mexico: 2006 = 8.1 2011 = 23.7 = 290% Increase
In the United States I'm savy enought to know that areas of certain cities aren't ideal tourist destinations, in Mexico, who knows ?????
And that corruption is the rule of thumb in the local police depts it's a no brainer, when you need help, there often isn't any. Even the locals often don't like to call the police when they need help.
I used to enjoy travel to Mexico but, just based on personal experiences, no mo for this gringo.....