In the North East of the USA the Mafia, La Cosa Nostra, whatever you want to call them, are the major organised crime threat. The FBI regularly bust these families for labour racketeering, contract manipulation, bookmaking etc. I think the nature of the organisation means that the FBI are vigilant against them. Certainly in areas like New York, Boston, Chicago etc these organisations have proved relatively resiliant. Also, they have their colleagues in Italy who can help them - during the 1980s the Sicilian mafia exported billions of dollars worthof heroin to the US and the FBI mounted raids on both American and Sicilian mafioso a few years ago.
One massive factor in the mafia now is the illegalityof some forms of gambling. These bookies make millions of dollars on sports betting, the sort of thing that you can do on every single high street in Britain. Same with video poker - a Chicago mobster got 25 years in prison earlier this year for bombing a rival 'vending machine' company and his biker cohort got 60 years for this and other offences.