This period of time is characterized by the economic boom of the 1920s and the great depression of the 1930s. In the United States, the following economic policies were enacted between 1918 and 1939:
1921: Emergency Tariff
A temporary increase of rates on some imported agricultural products in order to ease the declining profits that farmer's within the United States were experiencing.
1922: Fordney-McCumber Tariff
A permanent solution to declining profits suffered by farmers and factories. This tariff attempted to equalize production costs across the globe, and permanently increased the tariff on imported goods.
1930: Smoot-Hawley Tariff
Increased tariffs on over 20,000 imported goods to levels never before seen.