Border Fences and the Mexican Drug War
The Secure Fence Act resulted in the construction of 649 miles of fencing along the US-Mexico border. At the same time, violence in the Mexican drug war spiked as drug cartels fought to control territory. I hypothesize that construction of the border fence caused fighting between drug cartels by changing the value of territory for smuggling, undermining agreements between cartels. I use novel fine-grained data on violence from death certificates, engineering maps of the border fence, and a difference in differences research design to show that construction of the fence caused at least $3,000$ additional deaths in the border region. The entire effect of border fence construction is due to escalation of violence in areas where smuggling routes were not blocked by the new border fence—territories that became relatively more valuable for smuggling.
How Information Cascades Cause Refugee Crises: Evidence from Kosovo
Refugee crises repeatedly surprise the international community with their size and suddenness, yet we know little about what drives them. I develop a theory of refugee crises in which civilians living in conflict zones make individual decisions to flee in response to new information about the risk of victimization in war. The information conveyed by observing refugees fleeing can result in an information cascade, in which waves of refugees fleeing cause other civilians to increase their beliefs about the risk, increasing the numbers of subsequent refugees. To test this theory, I construct a geocoded village-day level dataset of refugee flows, violence against civilians, and the actions of armed groups during the Kosovo war. I develop an instrumental variables estimation strategy using the spatial network of villages connected by roads and the fact that refugees fled toward a single border crossing to estimate the causal spillover effect of refugees fleeing. I find that on average a refugee fleeing causes more than one additional civilian to flee.
Cell Phones and Internal Displacement in Civil War
Nationalistic Education and the Malleability of Ethnicity in Moldova
The Effect of Exposure to Immigrants on Anti-immigrant Sentiment
(with Barbara Maria Piotrowska)