[165] Hoover refused to become closely involved in the congressional debate over the tariff, and Congress produced a tariff bill that raised rates for many goods.[166] Despite the widespread unpopularity of the bill, Hoover felt that he could not reject the main legislative accomplishment of the Republican-controlled 71st Congress. Over the objection of many economists, Hoover signed the Smoot–Hawley Tariff Act into law in June 1930.[167] Canada, France, and other nations retaliated by raising tariffs, resulting in a contraction of international trade and a worsening of the economy.[168] Progressive Republicans such as Senator William E. Borah of Idaho were outraged when Hoover signed the tariff act, and Hoover's relations with that wing of the party never recovered.[169]

Later policies
Hoover in the Oval Office with Ted Joslin, 1932
By the end of 1930, the national unemployment rate had reached 11.9 percent, but it was not yet clear to most Americans that the economic downturn would be worse than the Depression of 1920–21.[170] A series of bank failures in late 1930 heralded a larger collapse of the economy in 1931.