In 1930, Congress decided that the answer to an economic downturn was to back American producers against foreign competitors. The Smoot-Hawley Tariff Act imposed levies on some 20,000 imported goods. It horrified economists, as well as President Herbert Hoover, who described it as “vicious, extortionate, and obnoxious.” But such was the public mood that Hoover felt he had no option but to sign it into law.