Why and how did Prohibition fail?

Prohibition failed in the 1920s because a large number of Americans like to have a drink or two. The problem with prohibition was not that the law was violated, but that so many people were violating the law. While there were a number of gangs before prohibition, they were mainly local. Prohibition saw a number of criminal organizations go regional and/or national in order to supply the nation's demand for alcohol. The failure of prohibition was quickly realized and the 21st Amendment made a speedy journey through the Constitutional process to revoke the 18th Amendment.