Why do trade costs vary?

As tariffs have fallen, it is apparent that trade costs are a significant obstacle to international trade and that they vary from country to country. The gap between the cif and fob value of a trade flow is a useful measure of aggregate trade costs, but only if the measure is based on a consistent volume of trade; mirror statistics are unsuitable. Using high quality Australian import data disaggregated at the HS 6-digit level, we find large country-by-country variations in trade costs. Distance, weight and size account for part of the variation in trade costs. Indicators of institutional quality pick up some of the variation in trade costs, but the relationship is not uniform across mode of transport and commodities; exporting countries' institutional quality is more strongly related to trade costs for air freight than sea freight, and the relationship is commodity-specific and strongest for manufactured goods. Country-specific characteristics influencing trade costs provide a link between institutions and economic development.