More than 1,000 economists have sent a letter to the president and Congress warning against “a host of new protectionist activity.” Citing a similar letter sent on May 3, 1930, which warned against the Smoot-Hawley Tariff Act, the economists say they fear “threats to withdraw from trade agreements, misguided calls for new tariffs in response to trade imbalances, and the imposition of tariffs on washing machines, solar components, and even steel and aluminum used by U.S. manufacturers.” Congress, the economists...