Transportation Infrastructure in the US ∗ Gilles Duranton

We document the quantity and quality of us roads, bridges, buses and subways in each year over the last 20 to 30 years. Next, we investigate total expenditure and the unit cost for each type of infrastructure over about the same time period. Third, we survey available estimates of the effects of infrastructure on various sorts of economic activity. Finally, we propose a simple theoretical framework with which to organize this information and to think about whether current investments can be rationalized as a part of a socially optimal infrastructure policy. This analysis suggests that the marginal contribution to mobility is lower for us transit expenditure than for highway expenditure.