The most far-reaching version of Trump’s strategy would raise the effective, or average, tariff on U.S. imports to about 20%, comparable to the heavy import duties the nation imposed in the 1930s and that contributed to the Great Depression, Zandi said. Before Trump took office, the average U.S. tariff rate was about 3%.

Many countries' recession chances raised greatly Wednesday with Trump's tariff announcement, a Fitch economist said, especially if they last long.