Alfred Eckes devotes an entire chapter to defending the Smoot-Hawley Tariff in his book, "Opening America's Market: U.S. Foreign Trade Policy Since 1776." If I remember correctly, Eckes argues that it was in some ways a tariff reduction, but that, in any case, it had little to do with causing or worsening the Great Depression. As the quote from Shiller suggests, the U.S. had significant tariff protection for its industry in the late 19th and early 20th centuries.