Transportation Costs, Agricultural Productivity and Cross-Country Income Differences

There are large differences in transportation infrastructure across nations. Constructing a measure of transportation infrastructure density for a large set of countries, I show that the disparity in this measure between the 5% income rich and the 5% income poor countries is a factor of 28. Are these differences a source of productivity differences across nations? Using a three-sector, two-region, general equilibrium model, I show that high transport costs can distort the allocation of resources not only across geographically dispersed production units within sectors but also between agriculture and non-agriculture. Taking as given the observed differences in transportation infrastructure densities, I quantify the role of transportation for cross-country income differences. The calibrated model produces an income disparity of 10.9 between the 5% rich and 5% poor countries. This corresponds to an improvement of 35% relative to the disparity predicted by a two sector model of agriculture and non-agriculture. Furthermore, the effects of advancements in transportation are non-linear: the elasticity of aggregate labor productivity with respect to the stock of transportation infrastructure in the poorest nations is 15 times higher than in the richest ones