We characterize optimal urban transportation policies in the presence of congestion and environmental externalities and evaluate their welfare and distributional effects. We present a framework of a municipal government that implements different transportation equilibria through its choice of...

Traffic fatalities are the leading cause of mortality in the United States despite being preventable. While several policies have been introduced to improve traffic safety and their effects have been well documented, the role of transitory health shocks or situational factors at explaining...

Transportation infrastructure is vital for the smooth functioning of international trade. Ports are a crucial gateway to this system: with more than 80% of trade carried by ships, they shape trade costs, and it is critical that they operate efficiently. Yet ports are susceptible to disruptions,...

Following Uber-initiated fare increases, drivers make more money per trip and, initially, more per hour-worked. Drivers begin to work more hours. However, this increase in hours-worked--combined with a reduction in demand from a higher fare--has a business stealing effect, with drivers spending...

This paper considers the evolution of global transportation usage over the past half century and its implications for supply chains. Transportation usage per unit of real output has more than doubled as costs decreased by a third. Participation of emerging economies in world trade and...

We propose a theory-inspired measure of the accessibility of a city's center: the size of the surrounding area from which it can be reached within a specific time. Using publicly available optimal-routing software, we compute these "accessibility zones" for the 109 largest US and European...

What is a feasible and efficient policy to regulate air pollution from vehicles? A Pigouvian tax is technologically infeasible. Most countries instead rely on exhaust standards that limit air pollution emissions per mile for new vehicles. We assess the effectiveness and efficiency of these...

Optimal transportation policies depend on demand elasticities that interact across modes and vary across the population, but understanding how and why these elasticities vary has been an empirical challenge. Using an experiment with Uber in Egypt, we randomly assign large price discounts for...

How does the interplay of geography and political-economic forces affect the shape of nations? This paper presents a quantitative framework for characterizing the equilibrium evolution of national boundaries in a world with a rich geography. The framework delivers simple equilibrium conditions...

Conventional wisdom proposes deep historical roots for authoritarianism in Africa: either colonial "decentralized despotism" or enduring structural features. We present a new theoretical perspective. Africans sought autonomous local communities, which constrained precolonial rulers. Colonizers...