Out of work people selling apples on the streets. Economic theorists argue therefore that overproduction caused the Great Depression. Workers made too little to buy everything the US industrial plant produced.
High tariffs sound good because they protect American industry.
They can also injure a nation's economy. The Smoot-Hawley tariff was one of the highest in our nation's history. Because other countries had difficulty selling in the US, they could not earn money. And if they couldn't earn money, they couldn't make loan payments dating back to WWI, nor could they purchase American products. That's why President Herbert Hoover urged FDR to participate in the London Economic Conference, the last world-wide attempt to fix the international causes of the Great Depression.