http://en.wikipedia.org/wiki/Tariffs_in_United_States_history
http://en.wikipedia.org/wiki/List_of_recessions_in_the_United_States
It is interesting how an increase in tariffs or some other trade restriction triggered each of the depressions in US history.
It is also interesting how the magnitude and frequency of recessions has gone down as tariff rates have dropped.
U.S. imports decreased 66% from US$4.4 billion (1929) to US$1.5 billion (1933), and exports decreased 61% from US$5.4 billion to US$2.1 billion, both decreases much more than the 50% decrease of the GDP. Thus exports minus imports which is the GDP formula declined from 1 billion to 600 million while GDP was 58.9 billion-a trivial effect on GDP of about 2/3 of 1%.
How many times must this myth be busted? Get an new lie, this one has been dispelled comrade.