That maybe but if we had exported our manufacturing plants to Germany, Japan and China we would have lost WW II. Thank you Smoot Hawley.
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, downplay the Smoot-Hawley's effect on the entire U.S. economy.[19]
Tariffs against China are a good idea, I am not sure about 25% but maybe 10% would be good. We are in a trade war already, we haven't fought back yet. Trump is right about this.
And I have to add this:
If we had not built the huge hydro projects that were rammed through the Congress in the 30’s, we also would not have won WWII.
People today do not appreciate how much of the electrical power abundance of WWII was a purely fortuitous outcome of the government trying to create jobs with the hydro dam projects and the REA. I remember reading somewhere that in 1944, the Manhattan Project was consuming about 40% of all power generated in the US, and another big chunk of power was going into aluminum smelting that in turn was used to produce aircraft. Aluminum smelting takes huge amounts of power even today.
We had that power at that time purely by accident. Projects like the TVA and Grand Coulee Dam on the Columbia helped us win the war as well.