This article is from the can.talk.guns FAQ, by Skeeter Abell-Smith firstname.lastname@example.org with numerous contributions by others.
Canada has not had "easy access to firearms" since at least 1978, and
the rises and drops in crime, violent crime, and homicide rates, do not
correspond to changes in our anti-gun laws.
Areas that have instituted tougher restrictions on the legal access or
ownership of firearms have seen increases in the violent crime rates.
Canada and Britain have both increased the restrictions on firearms
owners in the last 15 years, and have seen dramatic increases in violent
crime and the use of illegal firearms. Areas of the US (and several
countries) that have liberal restrictions, or have eased their
restrictions on legal gun owners have low crime rates, or have seen
their crime rates drop. See the John Lott and David Mustard paper
Crime, Deterrence, and Right-to-Carry Concealed Handguns at
http://law.lib.uchicago.edu/faculty/lott/guncont.html for more informat
on the ensuing reduction of crime and violence after concealed carry
laws were introduced.
Prior to January 1978 when Bill C-51 came into effect, Canada had very
liberal gun laws. From 1977 to 1991, Canada's violent crime rate has
increased 89% (583 to 1099 violent crimes per 100,000 population)
compared to a 59% for the US in the same period. (476 to 758 violent
crimes per 100,000 population). While the Canadian rate has been
decreasing since 1991, the same is true of the US rate. (Besides, a 4%
decrease hardly compensates for a 400+% increase!)
Too often the firearm homicide rates, or worse, the raw numbers, of
different countries are compared to each other without the overall rates
or non-firearm rates being noted. (Rates should always used as they
take into account population differences.) Obviously, a country with few
firearms will have a very low firearm-homicide rate, but the overall
homicide rate could easily be as high or higher than that of a country
allowing legal access to firearms. Providing only homicide by firearm
numbers, or rates, is dishonest and biases the reader by presenting the
data in a very misleading way.
As previously mentioned, if a prohibition somehow eliminated all
firearms, and, therefore, all firearm-related homicides, _without_ those
homicides becoming non-firearm homicides (i.e. no one simply uses
another weapon or bare hands), the US murder rate would still be roughly
_double_ the Canadian rate. If the USA without firearms would have more
murders per person than Canada with firearms, there must be other
factors at work.
Coalition For Gun Control fact sheet.
 U.S. Source: "Uniform Crime Reports for the United States
1991", Federal Bureau of Investigation, p.58; Canadian Source:
"Crime Trends in Canada 1962-1990", Cdn. Ctr. for Justice