It was claimed that alcohol caused many social problems, like violence and immorality and some people mainly strict christians and southerners thought if it were to be banned the USA would become a better place.
Anti-alcohol pressure groups campaigned effectively for prohibition the most famous was the Anti-Saloon League. The propaganda during WW1 to gain support left an anti-german feeling and many of the USA's brewers were of German descent.
The results of prohibition meant saloons were closed down, prices of alcohol rose and consumption decreased at first. Prohibition mad alcohol more attractive, illegal bars called "speakeasies" opened all over the country and the consumption of alcohol rose.