This probably came because of the creation/rise of gangs, an organization dealing with things very similar to the Mafia.
The sale of drugs, perhaps?
It's also a possible consequence of Nixon's War on Drugs [2]
[1] http://www.amazon.com/Gang-Leader-Day-Sociologist-Streets/dp...
[2] http://en.m.wikipedia.org/wiki/War_on_Drugs
This probably came because of the creation/rise of gangs, an organization dealing with things very similar to the Mafia.