Cross-Border Spillover: U.S. Gun Laws and Violence in Mexico

Abstract

Does access to arms promote violent crime? We exploit a natural experiment induced by the 2004 expiration of the U.S. Federal Assault Weapons Ban to examine how the subsequent exogenous increase in the availability of lethal weaponry affected violence in Mexico. The expiration relaxed the permissiveness of gun sales in border states such as Texas, Arizona and New Mexico, but not California, which retained a pre-existing state-level ban. Using mortality statistics over 2002-2006, we show that homicides, gun-related homicides and crime gun seizures increased differentially in Mexican municipios located closer to entry ports in these other border states, relative to entry ports in California. Our estimates suggest that the U.S. policy change caused at least 239 additional deaths annually in municipios near the border during post-2004 period. The results are robust to controls for drug trafficking, policing, unauthorized immigration, and economic conditions in U.S. border ports, as well as drug eradication, military enforcement, and trends in income and education in Mexican municipios. Our findings suggest that U.S. gun laws have exerted an unanticipated spillover on gun supply in Mexico, and this increase in arms has fueled rising violence south of the border.

Keywords: gun laws, crime, conflict

JEL Classification: D74, K4