The Cost of Gun Control.
"Using cross-sectional time-series data for U.S. counties from 1977 to 1992, we find that allowing citizens to carry concealed weapons deters violent crimes, without increasing accidental deaths. If those states without right-to-carry concealed gun provisions had adopted them in 1992, county- and state-level data indicate that approximately 1,500 murders would have been avoided yearly. Similarly, we predict that rapes would have declined by over 4,000, robbery by over 11,000, and aggravated assaults by over 60,000. We also find criminals substituting into property crimes involving stealth, where the probability of contact between the criminal and the victim is minimal. Further, higher arrest and conviction rates consistently reduce crime. The estimated annual gain from all remaining states adopting these laws was at least $5.74 billion in 1992. The annual social benefit from an additional concealed handgun permit is as high as $5,000."
-From Crime, Deterrance, and Right-to-Carry Concealed Handguns, Lott and Mustard, Journal of Legal Studies, January 1997.