for the United States but also with reference to the wider world. We establish the outlines of international integration a … century ago and analyze the institutional and informational impediments that prevented the late nineteenth century world from … achieving the same degree of integration as today. We conclude that the world today is different: commercial and financial …

, Europe, and Oceania for the period from 1870 to 2000 and demonstrate an overriding role for declining trade costs in the pre-World … War I trade boom. In contrast, for the post-World War II trade boom we identify changes in output as the dominant force …