See Anne Applebaum, alleged genius, by Village Standards, wank:
But whatever their ideology, and whatever their credentials, most of the pundits, historians and economists who debate the Great Depression agree about one thing: Whatever may have caused the crisis, protectionism, trade barriers and, yes, the Smoot-Hawley Tariff Act, helped to ensure that it lasted as long as it did.
Site linked to by "alleged genius" as her authority says:
In fact, few economists think the Smoot-Hawley tariff (as it is most often known) was one of the principal causes of the Depression.Worse mistakes were made, largely out of a misplaced faith in the gold standard and balanced budgets. America’s tariffs were already high, and some other countries were already increasing their own.
And, of course, the most essential point of the latter article is that Hoover did not listen to what most economists said -- which is actually the opposite of what the Obama is doing now -- but exactly what the GOP, the new Hoovers are doing.
You may also note that Ms. Applebaum manages to not to discuss NAFTA while singing the praises of all-out free trade.