The strongest organized crime unit in the world is the Taiwanese triad according to unclassified Interpol reports. It's so bad that Interpol doesn't even acknowledge their existance. It's known that the Italian mafia, Japanese yakuza and the breakaway triad groups around Asia reports to them. Even then, they only report to the so called No.2 of the group.

The gangs in America like the Bloods, Crips, Hells Angels, 18th Street Kings, MS-13, Mexican Mafia are independant groups with substantial manpower and influence to operate as a single unit. Then again, where there's a Chinatown, there's gonna be tongs or triads.