Fricciones en el comercio interregional: una aproximación basada en datos municipales

The border effect literature emphasizes the negative effect of distance on the international trade flows in favor of a greater proportion of trade within the national countries. However, recent works have shown that the border effect arises from a methodological error in measuring the distances within the international trade, having practically no effect when it is measured with the highest level of disaggregation. In this context, and using a micro-dataset about shipments by road within Spain during the period 2003-2007, we decompose the municipal trade flows into the intensive and extensive margin using different measures of transport costs, geographical distance and time, defined at the highest level of detail. Thus we see that, considering very detailed flows, the extensive margin increased a lot along the time, although the number of shipments (extensive margin) drops more sharply with increasing distance and time than the average value of such shipments (intensive margin). In contrast with previous studies, we find that the difference between the intensive and extensive margin is minimal when we consider time instead of distance. Furthermore, the total value of trade within the same municipality is much more important when we consider the time evolution (years). Finally, we find that regional borders have different effects on both margins, indeed provinces and autonomous regions don’t have a strong impact on trade, especially on the intensive margin. These findings provide more evidence about the “illusory” border effects problems that arise if statistical distance is measured in the aggregate rather than considering more detailed measures.