- High tariffs in the 19th century U.S. did not cause economic growth; recent research suggests they were incidental or harmful.
- The U.S. economy boomed during the late 19th century despite high tariffs, not because of them.
- Correlation between high tariffs and growth in the 19th century does not imply causation; other factors like population growth and technological innovation played significant roles.
- Economic analysis emphasizes the need for counterfactuals to isolate the causal effects of tariffs from other growth drivers.
- Industry-level studies and natural experiments provide better evidence than temporal coincidences for evaluating the impact of tariffs.