The end of Prohibition
During the Prohibition era, there are lots of problems and one of them was crime, gangsters who also supply illegal alcohol and urban people who use to drink and so the law means nothing. Although the police officers and FBI agents were sent off to stop those gangsters and crimes but there are far too many of them. There are more reasons to investigate "why Prohibition in the USA fail?"
In the late 1920s, more and more American found the idea of repeal increasingly attractive. One of the reasons was the governments failure to enforce the law. Also there are some organizations against Prohibition, for example: the Association Against the Prohibition Amendment (AAPA), these organization consist of wealthy and influential citizens in all state who were drinking and who fear that though Prohibition the federal government might permanently compromise the tradition of individual freedom.
So in 1933 when the new President, F.D. Roosevelt was elected, the Congress pass the 21st Amendment which would repeal the 18th Amendment. Following the repeal, liquor control again became a state rather than a federal problem. The annual per capita consumption of absolute alcohol in the country rose after the repeal from 4.5 liters in 1935 to 10.2 liters in 1975, but most state still retain restriction on the sale and consumption of alcohol.