I thought Smoot-Hawley had a lot to do with the depression.
Smoot-Hawley put the nail in the coffin for Hoover's political career. Of course, there are many on this site who believe that if we "raised tariffs" to "pertect factory jahbs" we would go back to being a blue collar, smokestack nation again. It was STUPID then and is STUPID now.
Smoot-Hawley probably did not cause the initial downturn but it was instrumental in turning a garden-variety recession into a full-scale depression.