Answer: Prohibition
Explanation: Due to the large number of immigrants who arrived in the US during the period preceding the 1920's, there has been an increase in the number of people without jobs, crime, bullying, violence, etc. Proponents of the ban argued that a ban on alcohol sales would reduce crime and alcoholism. However, the ban has in reality encouraged illegal transport, bottling and sale of alcohol. This again increased crime due to the myriad of gangs involved in the illegal sale of alcohol, and the period was known for unprecedented gang clashes due to a desire to dominate the black alcohol market.