During World War II, the Department of Foreign Affairs and other government agencies worked on plans to rebuild world trade and payments. They discovered significant gaps in the trade agreement agenda and concluded that they could make progress through simultaneous multilateral negotiations. After the war, President Harry S. Truman took advantage of RTAA to allow the United States to join 23 separate countries conducting bilateral customs negotiations on a product-based basis, with each country negotiating its concessions on each imported product with the main supplier of that commodity. The various bilateral meetings were summarized as part of the General Agreement on Tariffs and Trade (GATT) signed in Geneva on 30 October 1947. Democrats voted much more in favor of trade liberalization than Republicans, but were not consistent in their preferences. Mp Henry Rainey (D-IL) and members of Roosevelt`s government, Rexford Tugwell, Raymond Moley and Adolf Berle, were skeptical of tariff reductions during the Depression. However, the government decided to use a Democratic-controlled congress and presidency to impose the RTAA. In 1936 and 1940, the Republican Party ran on a platform to lift tariff reductions guaranteed under the RTAA. But when they reclaimed Congress in 1946, they did not act to remove tariffs. In the years since the adoption of the RTAA in 1934, the economies of Europe and East Asia had been decimated by the violence of World War II, which left a huge global production gap filled by American exporters.

[2] During the war, the United States had the highest positive balance in its history. Republican preferences for tariffs began to shift as exporters in the home districts began to benefit from stronger international trade. In the 1950s, there was no statistically significant difference between Republicans and Democrats on customs policy, a change that has lasted ever since. [3] Although Congress has entrusted the Ministry of Foreign Affairs with primary responsibility for negotiations with other nations, it has instructed the Customs Commission and other government authorities to participate in the development of a list of concessions that could be made abroad or requested abroad in exchange. Any trade agreement should adopt the principle of “unconditional treatment of the most favoured nation” and allow for a reduction in import duties of up to 50% of the Smoot-Hawley level. When U.S. tariffs fell dramatically, global markets were also increasingly liberalized. Global trade has undergone a rapid transformation. The RTAA was a U.S. law, but it provided the first widely used system of guidelines for bilateral trade agreements.

The United States and European nations began to avoid beggar neighborhood policies that pursued national trade objectives at the expense of other nations. Instead, countries have begun to realize the benefits of trade cooperation. From there, the President was granted, during the rounds and negotiations on the free trade area at the GATT (later the WTO), the negotiating powers of non-tariff measures in the respective legislation, such as the Trade Act of 1974, but the power to reduce tariffs was generally similar to that of the RTAA.