Arid regions of Africa are expanding by thousands of square kilometers a year, potentially disturbing pastoral routes that have been forged over a long period of time. This disturbance is often said to explain why "herder-farmer" conflicts have erupted in recent years, as pastoralists and...

We investigate the long-run effects of cooling on conflict. We construct a geo-referenced and digitized database of conflicts in Europe, North Africa, and the Near East from 1400-1900, which we merge with historical temperature data. We show that cooling is associated with increased conflict....

We use variation in exposure to victimization of 1,537 households of eastern Congo for each year of 1990-2013 to examine the formation of preferences to participate in armed groups. In this context, most armed groups are Congolese militia, whose objective is fighting foreign armed groups. We...

Mechanism design teaches us that a mediator can strictly improve the chances of peace between two opponents even when the mediator has no independent resources, is less informed than the two parties, and has no enforcement power. We test the theory in a lab experiment where two subjects...

We use census data for the US, Canada, Spain, and UK to estimate bilateral migration rates to these countries from 25 Latin American and Caribbean nations over the period 1980 to 2005. Latin American migration to the US is responsive to labor supply shocks, as predicted by earlier changes in...

In recent years, cases in which state governments chose to override federal environmental regulation with tighter regulations of their own have become increasingly common, even for pollutants that have substantial spillovers across states. This paper argues that this change arose at least in...

This paper reviews the economics approach to conflict and national borders. The paper provides a summary of ideas and concepts from the economics literature on the size of nations; illustrates them within an analytical framework where populations engage in conflict over borders and resources,...

We develop a theory of interstate conflict in which the degree of genealogical relatedness between populations has a positive effect on their conflict propensities because more closely related populations, on average, tend to interact more and develop more disputes over sets of common issues. We...

We report on an on-going project, which asks a number of questions relevant to the study of state capacity. What are the main economic and political determinants of the state's capacity to raise revenue and support private markets? How do risks of violent conflict affect the incentives to invest...

The conventional wisdom in political science is that for a democracy to be consolidated, all groups must have a chance to attain power. If they do not then they will subvert democracy and choose to fight for power. In this paper we show that this wisdom is seriously incomplete because it...