In 1929, President Hoover appointed an 11-member commission to look at Prohibition. The Wickersham Commission had law enforcement professionals and criminologists, took two years and produced massive report of 14 volumes that exhaustively documented that enforcement of the Volsted Act was ineffective, that police were often corrupt or incompetent to halt bootlegging, that crime rates and gang activity were high. Then it recommended more enforcement, more police, anti-corruption measures. Only one member refused to sign the report, instead making a separate statement that Prohibition should be repealed. Franklin P. Adams immortalized the report with a brief verse:

Prohibition is an awful flop.

We like it.

It can't stop what it's meant to stop.

We like it.

It's left a trail of graft and slime

It don't prohibit worth a dime

It's filled our land with vice and crime,

Nevertheless, we're for it.

What changed in the next two years was the appearance of a constituency against Prohibition. The Temperance groups had mobilized a very strong constituency in support of Prohibition and won, in 1920. Even though there were far more people who had no problem with the drinking of wine, beer, brandy, etc. and large businesses - brewers, bar owners, distillers- that profited by it, there was, at that time, no organized opposition. By 1933, those business groups got more organized, could claim repeal would help the economy, and were able to channel widespread dislike of the Act into legislation. In the middle of the Great Depression, with widespread misery, someone also came up with the perfect sales pitch: why not let the poor working man have his beer?