The American Mafia (or simply the Mafia or Mob in the United States), is an Italian-American criminal society. Much like the Sicilian Mafia, the American Mafia has no formal name and is a secret criminal society. Its members usually refer to it as Cosa Nostra (Italian for "our thing"). The press has also coined the name "National Crime Syndicate" to refer to the entirety of U.S. organized crime, including the Mafia. The Mafia emerged in New York's Lower East Side and other areas of the East Coast of the United States during the late 19th century following waves of Italian immigration, especially from Sicily. It has its roots in the Sicilian Mafia, but is a separate organization in the United States. Neapolitan, Calabrian, and other Italian criminal groups, as well as independent Italian-American criminals, eventually merged with the Sicilians to create the modern pan-Italian Mafia in North America. Today, the American Mafia cooperates in various criminal activities with the Sicilian Mafia and other Italian organized crime groups, such as Camorra, 'Ndrangheta, and Sacra Corona Unita.
The Mafia is currently most active in New York City, New Jersey, Philadelphia, New England, Detroit and Chicago, with smaller families, associates, and crews in places such as Los Angeles, Texas, Florida and Las Vegas. There have been at least 26 cities around the United States with Cosa Nostra families, with many more offshoots, splinter groups and associates in other cities. There are five main New York City Mafia families, known as the Five Families: the Gambino, Lucchese, Genovese, Bonanno and Colombo families. At its peak, the Mafia dominated organized crime in the U.S. While each crime family operates independently, nationwide coordination is provided by the Commission, which consists of the bosses of each of the strongest families.
Law enforcement still considers the Mafia the largest organized crime group in the United States. It has maintained control over much of the organized crime activity in the United States and certain parts of Canada (See Rizzuto crime family). Today most of the Mafia's activities are contained to the Northeastern United States and Chicago where they continue to dominate organized crime despite the increasing numbers of street gangs and other organizations that are not of Italian origin.