The Smoot-Hawley act was signed into law in June 1930, with most provisions not taking effect until one or two years later. It will probably forever be espoused as the cause of the depression, but no credible evidence exists for that contention. Foreign trade was a much smaller portion of the economy than it is today.
It is well documented, but not widely reported that Hoover raised taxes, prior to and after the 1929 crash. FDR further raised taxes. States, counties, and cities also raised taxes. And all of them continued raising taxes throughout the depression, and the depression lingered.
People quit investing in businesses, and businesses quit investing in themselves, because the government was taking the fruits of their labors. Do a search on depression + tax rates, and you will see the real cause of the depression.
The outsourcing problem could very well disappear were the US to abolish the income tax, social security and wage withholding, and replace them with the National Retail Sales Tax. Bills are moving in the House and Senate to do just this.
The NRST would abolish the IRS. Taxes would be paid at the final point of sale only. Taxes would apply equally to goods produced in the US and abroad.
The current wage withholding is essentially a tariff on American labor. With the NRST, the greatest disincentive to hire American workers would be removed.