Imports during 1929 were only 4.2% of the United States' GNP and exports were only 5.0%. Monetarists, such as Milton Friedman, who emphasize the central role of the money supply in causing the depression, note that the Smoot-Hawley Act only had a contributory effect on the entire U.S. economy.
We manufactured our own junk back then, we had a trade surplus. Trade was only 5% of GDP, Smoot Hawley could not have had a major impact on the Depression.