What was the end-result of the Smoot-Hawley Tariff Act?

As other countries placed tariffs on American exports in retaliation, these tariffs actually led to the reduction of American exports and thus jobs:

U.S. imports from Europe declined from a 1929 high of $1334 million to just $390 million in 1932, while U.S. exports to Europe fell from $2341 million in 1929 to $784 million in 1932. Overall, world trade declined by 66% between 1929 and 1934. [US Dept of State]

With the reduction of American exports came also the destruction of American jobs, as unemployment levels which were 6.3% (June 1930) jumped to 11.6% a few months later (November 1930). As farmers were unable to pay back their loans to banks, their loan defaults led to increasing bank crashes, particularly in the West and Mid-West.