We investigate the costs of transportation regulation using the example of agricultural markets in the United States. Using a large database of prices by state of agricultural commodities, we find that the coefficient of variation (as a measure of market integration between states) falls for...

We investigate the costs of transportation regulation using the example of agricultural markets in the United States. Using a large database of prices by state of agricultural commodities, we find that dispersion fell for many commodities until the First World War. We demonstrate that this...