See also: 1898 in organized crime, other events of 1899, 1900 in organized crime and the list of 'years in organized crime'.
A gang war breaks out between the Hip Sing and On Leong Tongs over illegal gambling in New York's Chinatown.
New York Black Hand leader Giuseppe Morello is arrested for counterfeiting and sentenced to three years. Released in 1902, Morello establishes a system where counterfeit $5 US dollar bills would be printed in Sicily and smuggled into the United States.
Ignazio Lupo, known as "Lupo the Wolf", arrives in New York.
Charles Umbriaco arrives in New York later joining the Black Hand under Giuseppe Morello and Ignazio Lupo.
Samson Melvin "Samoots", Chicago leader of Unione Siciliana
Louis Amberg, New York (Brooklyn) gangster
Anthony Carfano "Little Augie Pisano", Florida gambling racketeer
Joseph J. DiCarlo "Jerry the Wolf"; "Joe the Gyp", Stefano Magaddino gunman and Miami gambling racketeer
Murray Humphreys, Chicago Outfit member
Vincent John Rao (Frank Arra; Nunzio), Lucchese crime family consiglieri and associate of Willie Moretti
Jacob Shapiro, "Gurrah" Labor union racketeer
Abner Zwillman, "Longie" New Jersey Prohibition gangster
January 17 - Al Capone "Scarface", Chicago Mafia leader
December 1 - Gaetano Lucchese, Lucchese crime family founder
December 24 - Moe Dalitz Morris Barney Dalitz, Cleveland mobster and Las Vegas casino owner