Opening the black box of distance: evidence from Italy, 1862-1938

Historical studies of international trade have firmly established that distance was an important determinant of bilateral trade during the last two centuries. Despite the distance effect being one of the most robust results in trade history, we do not know much about how this effect changes over time, trade flows, across trading partners or traded goods. This paper examines the effect of distance on Italian bilateral trade comparing two periods: the first globalisation and the interwar years. Using a structural gravity model and data on Italian exports and imports by country and product and a new series of freights for the period 1862 to 1938, we find that the size and significance of the distance effect was highly contingent on the period and product composition of trade. While the trend in the effect of distance on trade during the first globalisation reflected the conventional story of the decline of transport costs during this period, the 1920s displays opposite trends for exports and imports. Further analysis of imports on the product-level reveals a similar heterogeneity of effect by product class. The distance elasticities of manufactured and industrial products reflected the overall trend, while those of raw materials and fuels did not seem to follow any clear pattern. We generate time series of trade to distance elasticities on the four-digit product category level and regress these on measures of trade costs and substitutability. We find that the distance effect at the product-level is explained by shifts in Italy's transport costs and the (gamma) elasticity of substitution across products.