The only reason Prohibition was finally instituted was they found a way to replace the taxes on alcohol that the Federal government ran on - watch Ken Burns' documentary on it, it's a well researched, even handed look at the whole history of Prohibition. There was a serious problem with alcohol in the US, because the Fed looked away at abuses of alcohol sales and it's impact on society, because most of the money they ran Washington on was from booze.

The thing that changed it? Income tax.