Since 1987 about half of the states have adopted laws that say anyone who meets certain objective criteria is entitled to carry a concealed firearm. Although gun control advocates said these laws would foster violence, the evidence indicates that, if anything, they have helped deter crime.
But a forthcoming study by University of Texas economist Stephen G. Bronars and University of Chicago law professor John R. Lott suggests that such deterrence does have a downside. The study, scheduled to appear in the May issue of American Economic Review, finds that crime rates tend to decline in areas with liberal carry-permit laws while rising in neighboring jurisdictions that make it harder for citizens to arm themselves.
Looking at county-level data from 1977 to 1992, Bronars and Lott report that "allowing citizens to carry concealed weapons leads to significant reductions in crime rates in every crime category (other than larceny) after four years." Their estimates, which take into account demographic differences and national trends, include four-year drops of 20.4 percent in murder, 13.1 percent in robbery, 4 percent in assault, and 2.8 percent in rape.
At the same time, for counties that do not recognize a right to carry, "a shall issue law in neighboring counties leads to significant increases in murders, rapes, robberies, property crimes, burglaries, and larcenies." These include short-term increases of 9.4 percent in murder and 7.1 percent in robbery.
Such spillover effects, Bronars and Lott argue, indicate that criminals are moving to areas where it's less likely they'll encounter armed victims. "Taken together," they conclude, "these results imply that concealed handguns deter criminals and that the largest reductions in violent crime will be obtained when all the states adopt these laws."