A student points me to Ron Paul on the 1920-21 depression.

In 1921 we had a severe depression; it was over in one year. A little bit later in the 30s we had another one but then the government decided to do all these things, bail everybody out. Exactly what we’re doing now and it prolonged the correction.

The implication is that in 1921 the government didn’t “do all these things”. But of course the government did adopt policies to restrict trade and immigration.

Interestingly, two of the first Hoover administration responses in 1930 were to restrict trade and immigration.

I think the lesson one would draw here is that policymakers, seeing that restricting trade and immigration went along with a swift end to the 1921 recession, tried them again in 1930. But they didn’t work. I don’t see any reason to conclude that the government opted not to intervene in 1921 and to intervene in 1930.