Did high tariffs raise or lower American manufacturing productivity?
Core argument: Using an instrumental variable strategy on 1870–1900 U.S. data, the authors find that tariffs reduced labor productivity in manufacturing, with negative and significant coefficients for textiles, metals, paper, transportation, chemicals, and petroleum.
We develop an industry-level database of tariffs spanning three decades (1870-1900) by digitizing the universe of tariff-lines and imports from official data in benchmark years. We match these data to state-level Census of Manufactures data for over 80 highly dis-aggregated manufacturing industries. Using an instrumental variable strategy, results show that tariffs reduced labor productivity. Generally, when labor productivity is the dependent variable, the coefficients on tariffs are negative and significant (Textiles, Metals, Paper, Transportation, Chemicals and Petroleum) or statistically insignificant (Consumer Goods, Tobacco, Glass, and Machinery/Electrical). Our results are consistent with several, not mutually incompatible, explanations. One is that tariffs weakened international competition, and in so doing, allowed smaller, less efficient firms to operate. Second, firms in a less competitive environment may have been less likely to invest in new products and processes. Finally, firms and industries may have lobbied to obtain protection which could have led to an economic misallocation of resources.

