Bohanon and Van Cott put an intriguing Julian-Simonesque spin on the point by noting that the immigrant labor that came freely to the U.S. circa 1870-1910 contained inchoate goods and services – goods and services that these immigrants would eventually actually produce once they began working in the U.S. economy. So, to admit an immigrant is to admit in — duty free! — a stream of goods and services. It is, in short, a means around high tariffs. Because immigration during these decades was so significant, Americans effectively imported, duty-free, many more goods and services (inchoate though they were) than is revealed by conventional trade statistics.
More information: Tariffs, Immigration, and Economic Insulation. Cecil Bohanon and T. Norman Van Cott (PDF).
