Got to love the Mises site.

Hoover expanded the money supply, increased government spending and attempted to bail out the banks. Everything the Keynesian school would prescribe for a recession. The result was a delaying of the market correction necessary to revive the economy. So why do we still operate on obviously flawed ideas? I have no idea.

Here is Rothbard's America's Great Depression. A whole book devoted to scholarly analysis of the event.
http://mises.org/rothbard/agd.pdf