Interesting. Perhaps the real cause of the trade barriers in 1929 were more Political than Economic. On the eve of the Great Depression, the USA had large trade surpluses and was attempting to maintain those surpluses going into the depression, effectively driving up unemployment across the rest of the world. Trade Barriers around the world were erected to level the playing field – and prevent America from exporting it’s unemployment problem.
In 2009, we could be seeing the same thing, but this time China may be the one exporting the unemployment problem. All I can say is: I hope we don’t see the return of protectionism!
See James Fallows of the Atlantic’s take on this: This does not bode well