The 18th Amendment, Prohibition, was passed during wartime to conserve grain and maintain a sober workforce. It prohibited the manufacture and sale of alcohol.
The Volstead Act was passed as a federal law to enforce prohibition.
Prohibition did not end either the distribution or the manufacturing of alcohol. Instead, bars known as speakeasies emerged, which sold bootleg liquor. Officials were laid to "look the other way." Even President Harding served alcohol and took part in gambling. Gangs emerged in this era, fighting for dominance over the bootlegging trade.
Women were generally strong advocates of the amendment.
This is a piece of propaganda from the era. It depicts a fat, wealthy man (a brewer) who is profiting from the "wet" vote. On the other hand, a struggling mother begs you to vote "dry" and help her.