Monetary tightening was not the only major policy error of the 1930’s; so was a retreat into protectionism, symbolized by the Smoot-Hawley tariff increases at the beginning of that decade. Historians continue to debate the centrality of the Smoot-Hawley law itself, but the subsequent tariff war certainly damaged trade and economic growth, making a bad situation worse.
货币紧缩并非20世纪30年代唯一的重大政策失误；除此之外还有保护主义复燃——以30年代伊始实行的斯穆特-霍利（Smoot-Hawley）关税法案为典型代表。经济史家仍然在为斯穆特-霍利法案本身的集中性争辩不休，但随之而来的关税战破坏了贸易和经济增长，让形势雪上加霜。