Violent Crime and the Overmilitarization of US Policing

Using new data at the police department level, I propose an identification strategy for estimating the causal effect that police militarization has on reducing violent crime. I show that previous estimates are likely to be contaminated by unobserved factors that simultaneously determine militarization and violent crime. Upon addressing this issue, I find a point estimate that is 20 times larger than those estimated previously. I then find that one-fourth of the effect of militarization is due to the displacement of violent crime to neighboring areas. Police departments overmilitarize because they do not consider this externality. These new findings have significant implications for the policy debate concerning the costs and benefits of police militarization (JEL H56, H76, K42).