Some interesting work done on crime rates vs. regional gun control laws to go along with some summery Friday Rule Five: An examination of the effects of concealed weapons laws and assault weapons bans on state-level murder rates. (link leads to a pdf document.) Key excerpt from the abstract:
Using data for the period 1980 to 2009 and controlling for state and year fixed effects, the results of the present study suggest that states with restrictions on the carrying of concealed weapons had higher gun-related murder rates than other states. It was also found that assault weapons bans did not significantly affect murder rates at the state level. These results suggest that restrictive concealed weapons laws may cause an increase in gun-related murders at the state level. The results of this study are consistent with some prior research in this area, most notably Lott and Mustard (1997).
And another from the conclusion:
Given that the average gun related murder rate over the period in question was 3.44, the results of the present study indicate that states with more restrictive CCW laws had gun-related murder rates that were 10% higher. In addition, the Federal assault weapons ban is significant and positive, indicating that murder rates were 19.3% higher when the Federal ban was in effect. These results corroborate the findings of Lott and Mustard (1997). These results suggest that, even after controlling for unobservable state and year fixed effects, limiting the ability to carry concealed weapons may cause murder rates to increase.
There may, however, be other explanations for these results. Laws may be ineffective due to loopholes and exemptions. The most violent states may also have the toughest gun control measures. Further research is 
warranted in this area.
Further research may be warranted, but the evidence that gun control has little to no effect on crime rates is better supported now than, say, anthropogenic climate change. The positive effects of liberalized concealed-carry laws is just as well documented.
Which makes the arguments – the tired, stale, old arguments – of gun control proponents all the more baffling. When Colorado’s concealed-carry law was being debated in the State legislature, we heard them all:
There will be shootouts over parking spaces.- People will be killed with their own guns.
- More handguns in the hands of citizens will mean more crime.
- Carnage will ensue from untrained people carrying guns.
None of these dire predictions came true – not anywhere. In fact, CCW permit holders are, as a group, some of the most law-abiding folks you’ll find anywhere.
But statistics aside, there is a matter of principle involved. Studies such as the one referenced above are useful in making arguments 
for public policy, to be sure, but the fact is that a free citizen should be able to make the choice for him or herself as to whether to carry a firearm for self-defense or defense of others.
I carry a gun for a variety of reasons; I’m too young to die and too old to get my ass kicked, I can’t carry a cop, I’d rather take my chances with twelve jurors than six pallbearers, and so on. But the primary reason I carry is this: I am a free, law-abiding citizen and it suits me to do so.
If we truly are a free country – if individual liberty still has any meaning – what other reason should be required?
