The 18th Amendment to the Constitution, passed and ratified with overwhelming support, prohibited the making, transporting or selling of intoxicating liquor. At the stroke of midnight on January 16, 1920, the United States was officially "dry" -- but that didn't mean people stopped drinking. Supplying the nation's continued desire for alcohol provided a new revenue stream for the criminal underworld, and many of these gangsters, including Chicago's notorious Al Capone, wielded legendary power.

Supply and Demand

The fact that alcohol was illegal didn't deter people who wanted to drink, and speakeasies -- secret spots often owned by gangsters, where moonshine and illegally-imported liquor were sold -- grew in popularity. Everyone in a speakeasy was technically a criminal, subject to arrest for drinking alcohol, and this commonality broke down social barriers. Men and women from all segments of society commingled. As demand increased, a Chicago gangster named Johnny Torrio realized there were major profits to be made in the distribution of liquor to speakeasies -- but there was too much competition. He needed someone who could organize his business and eliminate rival gangs -- and he knew just who to call. Torrio contacted an old New York associate named Alphonse "Al" Capone.

Brains for the Business

Capone moved his family to Chicago and set up shop as Torrio's right-hand man. By the mid-1920s, the pair had relocated their base of operations to the Chicago suburb of Cicero, where Capone -- through violence and intimidation -- succeeded in getting his own man elected mayor. Capone brought not just street smarts, but also accounting expertise he'd acquired while working as a bookkeeper for some of Torrio's past enterprises in New York. Torrio retired after he was injured in an assassination attempt, leaving his sprawling network in Capone's hands. By the end of the decade, Capone had a lock on nearly all alcohol supplied to any of Chicago's estimated 10,000 speakeasies.

Prohibition Profit and Risk Management

Newspapers in the 1920s estimated Capone's enterprises generated nearly $100 million a year. Federal agents determined that $60 million came from the distribution of illegal alcohol to speakeasies. All of that illegally-gained profit came at considerable risk, however. Capone lessened his legal risk by handing out steady bribes to police officers, politicians and judges. Other gangs were more difficult to handle. There was a lot of money to be made during the Prohibition Era, and every gangster wanted a piece of the action. Violence escalated to the point where murders were committed on city streets in broad daylight, and the fearful public pleaded with law enforcement to end the reign of terror. Capone called a "Peace Conference" with rival gangs, but the worst was yet to come.

Public Enemy Number One

On Valentine's Day in 1929, men dressed as cops descended on an illegal alcohol warehouse and distribution center that belonged to a Capone rival. The seven men working in the building were told to line up against the wall and then murdered in a hail of machine-gun fire. Capone was widely believed to have been behind the gruesome attack, although he was in Florida at the time. After the massacre, Capone was branded "Public Enemy Number One." Ultimately, Capone was arrested in 1931 on a federal indictment of 22 counts of tax evasion. The legendary gangster was in prison in 1933, when ratification of the 21st Amendment repealed the 18th Amendment and brought an end to the Prohibition Era.