What is the role of transport improvements in globalization? We argue that the nineteenth century is the ideal testing ground for this question: freight rates fell on average by 50% while global trade increased 400% from 1870 to 1913. We estimate the first indices of bilateral freight rates for the period and directly incorporate these into a standard gravity model. We also take the endogeneity of bilateral trade and freight rates seriously and propose an instrumental variables approach. The results are striking as we find no evidence that the maritime transport revolution was the primary driver of the late nineteenth century global trade boom. Rather, the most powerful forces driving the boom were those of income growth and convergence.

Poor countries are more volatile than rich countries, and we know this volatility impedes their growth. We also know that commodity price volatility is a key source of those shocks. This paper explores commodity and manufactures price over the past three centuries to answer three questions: Has commodity price volatility increased over time? The answer is no: there is little evidence of trend since 1700. Have commodities always shown greater price volatility than manufactures? The answer is yes. Higher commodity price volatility is not the modern product of asymmetric industrial organizations -oligopolistic manufacturing versus competitive commodity markets -that only appeared with the industrial revolution. It was a fact of life deep into the 18th century. Does world market integration breed more or less commodity price volatility? The answer is less. Three centuries of history shows unambiguously that economic isolation caused by war or autarkic policy has been associated with much greater commodity price volatility, while world market integration associated with peace and pro-global policy has been associated with less commodity price volatility. Given specialization and comparative advantage, globalization has been good for growth in poor countries at least by diminishing price volatility. But comparative advantage has never been constant. Globalization increased poor country specialization in commodities when the world went open after the early 19th century; but it did not do so after the 1970s as the Third World shifted to labor-intensive manufactures. Whether price volatility or specialization dominates terms of trade and thus aggregate volatility in poor countries is thus conditional on the century.

What has driven trade booms and trade busts in the past century and a half? Was it changes in global output or in the costs of international trade? To address this question, we derive a micro-founded measure of aggregate bilateral trade costs based on a standard model of trade in differentiated goods. These trade costs gauge the difference between observed bilateral trade and frictionless trade in terms of an implied markup on retail prices of foreign goods. Thus, we are able to estimate the combined magnitude of tariffs, transportation costs, and all other macroeconomic frictions that impede interna tional trade but that are inherently difficult to observe. We use this measure to examine the growth of global trade between 1870 and 1913, its retreat from 1921 to 1939, and its subsequent rise from 1950 to 2000. We find that trade cost declines explain roughly 55 percent of the pre– World War I trade boom and 33 percent of the post–World War II trade boom, while a precipi tous rise in trade costs explains the entire inter