As more and more U.S. industries began to benefit from tariff cuts, some of them began campaigning with Congress for lower tariffs. Until RTAA, Congress had been mainly pressured by industries that wanted to create or increase tariffs to protect their industry. This change has also helped to maintain many of the benefits of trade liberalization. In short, the political incentive to increase tariffs has diminished and the political incentive to reduce tariffs has increased.  Although the world has changed dramatically since the FDR passed the Mutual Trade Agreements Act, the basic trade promise remains the same. Well done, trade policy gives American workers the chance to compete in a level playing field, and under the TPA, Congress and the government unite to manage trade with global partners by setting goals and standards that defend American interests and values. The Reciprocal Tariff Act (adopted on 12 June 1934, Chapter 474, 48 Stat. 943, 19 U.C No. 1351) provided for the negotiation of customs agreements between the United States and various nations, including Latin American countries.
 The law served as an institutional reform to allow the president to negotiate with foreign nations a reduction in tariffs in exchange for a reciprocal reduction in U.S. tariffs. This has led to a reduction in tariffs. 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.  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.
 Reciprocity was an important principle of trade agreements negotiated under the RTAA, as it encouraged Congress to reduce tariffs. As more and more foreign countries have entered into bilateral tariff reduction agreements with the United States, exporters have been more encouraged to promote Congress in favour of even lower tariffs in many sectors.  Under the leadership of the United States and the United Kingdom, international cooperation flourished and concrete institutions were created.