While many countries do protect specific markets with high trade barriers, most advanced economies maintain similar tariff profiles. On a trade-weighted basis, the average U.S. tariff is 2.2 percent. Japan’s is 1.9 percent and the European Union’s is 2.7 percent, slightly higher than the U.S. average, according to the World Trade Organization.

Trump’s reciprocal plan could return the average U.S. tariff to its early 1930s level of around 20 percent, said Edward Gresser, a former trade official who is now the vice president and director of trade and global markets for the Progressive Policy Institute. Gresser said Trump’s actions would be unprecedented, and many experts have argued the president does not have the authority to impose such sweeping tariffs without congressional approval.