Other than driving up the demand for products like Coca-Cola, Prohibition was largely ineffective. Americans continued to drink, although not at previous levels.
Organized crime quickly filled the vacuum of legitimate saloons and alcohol dealers, allowing this criminal element to move beyond the ethnic neighborhoods they previously dominated. Mobster Al Capone owed his meteoric rise to the head of organized crime in Chicago directly to the policies of Prohibition. Just as Capone dominated Chicago, different crime leaders used the prohibition of alcohol as an avenue to illegitimate riches in other American cities. In the Bronx borough of New York City, gangster Dutch Schultz also worked his way up the organized crime ladder thanks to the opportunity to provide illegal alcohol. Source:
Prohibition and Crime