Siegel was not only influential within the Jewish mob but, like his friend and fellow gangster Meyer Lansky, he also held significant influence within the American Mafia and the largely Italian-Jewish National Crime Syndicate.
Siegel var ikke alene en central person i den jødiske mafia, men var som sin ven og gangster-kollega Meyer Lansky også indflydelsesrig i den italiensk-amerikanske mafia og det italiensk-jødiske forbrydersyndikat National Crime Syndicate.