If the trend is left unchecked, the world may repeat the experience of the 1930s, when industrial production fell by nearly 40 percent, unemployment soared, and economic activity remained anemic for the better part of a decade. Then as now, trade barriers did not cause the problems. America’s Smoot-Hawley Tariff Act did not trigger the Great Depression, and tariffs today will not have caused the COVID-19 depression. But such barriers could affect the recovery, especially given the modern importance of cross-border supply chains. What happens now will influence the shape the trading system will take for decades to come.