… is from page 29 of Kevin O’Rourke’s and Jeffrey Williamson’s 1999 book, Globalization and History (original emphasis):
All of the commodity market integration in the Atlantic economy after the 1860s was due to the fall in transport costs between markets, and none was due to more liberal trade policy. In contrast, most of the commodity market integration after the 1950s was (we suspect) due to more liberal trade policy.
DBx: Keep this fact in mind when you next encounter the assertion that America’s industrialization during the 19th century was fueled by protective tariffs – that is, fueled by reducing the flow of foreign goods into the United States. Even during those post-Civil War 19th-century periods when average U.S. tariff rates were highest, transportation costs (and communications costs) were falling rapidly. The falling costs of transportation and communication went far to undo the protective consequences of protective-tariff rates.