UC Berkeley

This dissertation considers the role that of various inputs in informing the market for crimes. Chapter 1 considers the "national" effect of immigration. Using panel data on U.S. cities and an instrument that leverages temporal variation in rainfall in different regions of Mexico and persistence in regional Mexico-U.S. migration networks, my findings indicate that Mexican immigration is associated with no appreciable change in the rate of either violent or property crimes in U.S. cities.

Chapter 2 leverages a natural experiment created by recent legislation in

Arizona to estimate the impact on crime of an extremely large and discrete

decline in the state's foreign-born Mexican population. I show that Arizona's

foreign-born Mexican population decreased by as much as 20 percent in the wake

of the state's 2008 implementation of the Legal Arizona Workers Act (LAWA),

a broad-based E-Verify law requiring employers to verify the immigration status

of new employees, coupled with severe sanctions for employer noncompliance.

In order to isolate the causal effect

of the passage and implementation of LAWA on crime, I leverage a synthetic

"differences-in-differences" estimator, using a new method of counterfactual

estimation proposed by Abadie, Diamond and Hainmuller (2010). In contrast to previous literature, I find

significant and large effects of Mexican immigration on Arizona's property crime

rate. Results are driven, in large part, by the fact that LAWA resulted in especially

disproportionate declines among Mexican migrants who are young and male and,

as such, the effects are predominantly compositional.

The final chapter, coauthored with Justin McCrary, considers the responsiveness of crime to police manpower. Using a new panel data set on crime in medium to large U.S. cities over 1960-

2010, we show that (1) year-over-year changes in police per capita are largely

idiosyncratic to demographic factors, the local economy, city budgets, measures

of social disorganization, and recent changes in crime rates, (2) year-over-year

changes in police per capita are mismeasured, leading many estimates in the

literature to be too small by a factor of 5, and (3) after correcting for measurement

error bias and controlling for population growth, a regression of within-state

differences in year-over-year changes in city crimes on within-state differences

in year-over-year changes in police yields economically large point estimates. Our

estimates imply that each dollar spent on police is associated with approximately

$1.60 in reduced victimization costs, suggesting that U.S. cities employ too few

police.