As of 2013, the Federal Bureau of Investigations (FBI) estimated that the five crime families in New York City has roughly 700 full-time members and up to 7,000 associates.
The NYC office of the FBI had roughly 36 agents who were assigned to investigating organized crime activities.
The five families of the Mafia in New York City are the Bonannos, the Colombos, the Gambinos, the Genovesse and the Lucheses.
Source: William K. Rashbaum, “F.B.I. Will Fight the Mafia With Fewer Investigators,” New York Times, June 28, 2013.