The answer to this question is rather complicated. If we look at just the alcohol consumption in the United States before and after Prohibition, we do see that directly after prohibition was enacted, alcohol consumption plummeted. In 1919, the consumption of pure alcohol per capita was about .8 gallons. In 1921, it was just over .2 gallons, as shown by Clark Warburton in the Economic Results of Prohibition.
However, in 1922, that went up to just above .8 gallons per capita, and a year later, it was nearly 1.2 gallons per capita.
What Warburton shows us is that leading up to prohibition, the amount of alcohol being consumed per capita was already steadily lowering. While the enactment of prohibition would make that rate plummet, directly after enactment, the rate would rise once again, and level off around 1 gallon per capita. According to the World Health Organization, that level today is just over 2.2 gallons per capita. Now, to be fair, that is pretty far below the all time high in 1830, which according to W.J. Rorabaugh, in Alcohol in America, was 7 gallons per capita.
As I said though, alcohol consumption had been on a decline for nearly a decade. And looking at the number, prohibition only seemed to reduce the amount of alcohol consumed for just a single year. After that, it would once again increase and level out around 1 gallon per capita for a substantial amount of time.
But we do have to jump back just a bit. Those numbers can be a bit misleading. Rorabaugh, for instance, mentions that in 1850, alcohol consumption had dropped in half from 1830. As he points out though, it wasn’t that Americans were drinking less per person, but that half the population had stopped drinking. So half the population continued to drink just as much.
However, as suggested, by 1910, alcohol was dropping, as shown by Warburton. Or more specifically, the consumption of pure alcohol, per capita, in gallons, was decreasing. That’s a bit misleading again though. From 1900 to 1913, Americans were actually drinking more alcoholic beverages, but what was happening is that the consumption of hard liquor was declining, while consumption of beer was rising, as Jack Blocker in Consumption and Availability of Alcoholic Beverages in the United States, 1863–1920 demonstrates. By the time prohibition had gone into effect, the consumption of beer and hard liquor was virtually equal. This meant less pure alcohol consumed per capita, but the amount of alcoholic beverages had gone up (it was just weaker).
And here comes a problem. Mark Thorton, in Prohibition was a Failure, shows that during prohibition, that changed. The consumption of beer nearly disappeared, while hard liquor again started being consumed in higher amounts.
All in all though, when it came to decreasing alcohol consumption, Prohibition just didn’t work. The reduction in consumption was short lived, and it soon rose to levels higher than what it was just prior to prohibition. That was also partly because before prohibition, in the decade leading up to that time, alcohol consumption was already lowering. What prohibition did do though is cause a spike in the consumption of hard liquor, and nearly destroyed the beer industry.
The outcome was even worse though. As Thorton points out, federal convicts had risen by 561 percent during the period of prohibition, prison populations rose by 366 percent. Two-thirds of all prison inmates had alcohol related charges.
Anneliese Anderson, in Organized Crime, Mafia and Governments, also shows that because of Prohibition, the growth of the mafia in the United States grew not only in scope, but also power. Prohibition created a major illegal market for alcohol, and that market was filled largely by the mafia.
