On June 17 President Herbert Hoover signed a law that was meant to avoid a nationwide depression but instead created one. The Smoot-Hawley Tariff Act boosted already high tariffs by 50 to 100 percent, to their highest levels in history, on virtually every American product that faced competition from abroad. Supporters confidently expected the act to fix the economic problems that had resulted from the previous autumn’s stock market crash. As the Senate’s Republican majority leader said during debate, “Within a year . . .