In this paper the impact of national borders on international trade within the European Union is considered. Using a gravity model, I find that, averaged over all EU countries, intranational trade is about ten times as high as international trade with an EU partner country of similar size and...

Why do borders still matter for economic activity? The reunification of Germany in 1990 provides a unique natural experiment for examining the effect of political borders on trade. With the fall of the Berlin Wall and the rapid formation of a political and economic union, strong and strictly...