January 16, 1920 — Prohibition officially begins in the USA

One of the most expensive and counter-productive intrusions of the government into the private sphere in human history, Prohibition was enabled by the 18th Amendment to the US Constitution. It banned the sale, production and consumption of alcohol throughout the United States. Naturally, it was immensely unpopular with the kind of people who like to drink alcohol, and these people, if they could not obtain their tipple legally, would do so illegally. The new law – which was also rather more heavily enforced on the poorer classes than than the richer, often by police known to drink themselves – lead to an incredible increase in the number and wealthiness of criminals, with a corresponding increase in violent crime.

Ultimately, Prohibition failed and was written out of law with another amendment to the Constitution, but the hand of organised crime had been strengthened in a way that, nearly a century later, law enforcement has still not brought back to pre-Prohibition levels.