It was almost impossible to enforce the Volstead Act. because of a range of issues.
There was a lack of public support. Many people were “wets” and it was impossible to persuade drinkers to change the habit of a lifetime. Plus, the law did not forbid the consumption of alcohol (only the manufacture, transport and sale of it), so many felt justified in drinking. President Harding reputedly flouted the law. In addition, non-WASPs, especially in the northern states, resented government interfering with their freedoms.
Alcohol was readily available. It was supplied by bootleggers, moonshiners and rum-runners. There were 280,000 illegal stills seized, and speakeasies were everywhere, including 30,000 in New York by 1929. Over 10 million prescriptions per year were issued for more than 1 million gallons of beer and the permits for communion wine increased.
Enforcement of Prohibition by government officials was very ineffective. Patrolling the thousands of miles of the USA’s borders with Canada and Mexico, both major routes for smuggling liquor, was impossible. Blocking the 29,000 km of coastline was also difficult. Rum continued to come in from the West Indies, especially as rumrunner’s boats were faster than those used by the governments. There were 2,300 special Prohibition Agents appointed by the Prohibition Bureau, but they were too few in numbers and were on low salaries ($2,500 per year) which meant they were prone to corruption. One in twelve agents were sacked for taking bribes. Judges and politicians were also often willing to take bribes. Only Eliot Ness and his Untouchables who were a group of US federal law-enforcement agents assigned to bring bootlegging to an end, were above corruption.
Prohibition led to the growth of organised crime gangs, like the Mafia, and gangsters, such as Al Capone. They not only supplied alcohol on a massive scale, but they also ran prostitution, gambling and other rackets. Thus, crime increased dramatically.