c 1900 - Giuseppe Morello (Born Corleone, Sicily, May 2, 1867. Killed New York City, Aug. 15, 1930). Known as "Piddu" or "Clutch Hand" (in erroneous reports as "Peter"), Morello and his brother-in-law Ignazio Lupo led a gang of extortionists and counterfeiters in Italian East Harlem, Manhattan's Lower East Side and Brooklyn. With the support of Sicilian/American Mafiosi like Vito Cascioferro and Pasquale Enea and with strong connections to Mafia organizations in New Orleans and Chicago, Morello was recognized as boss of bosses of the U.S. Mafia, perhaps the first man to hold that title. (Some have argued that Nicola Taranto and perhaps Candelaro Bettini, leaders of late 19th Century Sicilian-American counterfeiting rings, held the boss of bosses title earlier than Morello.) He was jailed in 1910 for counterfeiting. His organization subsequently broke down into the Genovese, Gambino and Lucchese Crime Families.
c 1910 - "Don Sebastiano" was identified by an informant to the U.S. Secret Service as a key administrative figure over the New York Mafia during the first years of Morello's imprisonment. It is possible that he temporarily held the boss of bosses title until Morello-Lupo legal appeals failed and a new election could be held.
c 1912 - Salvatore D'Aquila (Born Palermo c. 1873. Killed New York City, Oct. 10, 1928). Known to his underworld associates as "Toto," Palermo-born D'Aquila rose up through the ranks of the Morello Mafia. Originally based in the Bronx, and later a Mafia leader in Brooklyn, he secured the loyalty of a number of key pieces of the old Morello organization when it became clear that legal appeals by Morello and Lupo would not win them their freedom. D'Aquila was elected the new boss of bosses of the American Mafia, but he was unable to hold in line the various factions of the old Morello organization. He lost control of East Harlem and lower Manhattan. In an effort to increase his influence, D'Aquila is known to have inserted spies into various crime families across the country. After Morello's release from prison (and likely speculation over whether he should be returned to his old position), D'Aquila created a schism in the New York Mafia by passing a death sentence against Morello and his loyalists. Though the D'Aquila crime family is often said to be based in Brooklyn, the powerbases of D'Aquila and his two immediate successors actually were in the Bronx. Around 1925, D'Aquila left Brooklyn to return to his Bronx roots.
1928 - Giuseppe Masseria (Born Menfi, Sicily, Jan. 17, 1886. Killed Brooklyn, April 15, 1931). "Joe the Boss" Masseria, member of a lower Manhattan burglary ring, became standard-bearer for the remnants of the Morello-Terranova organization around 1922. A non-traditional Mafioso, Masseria welcomed many Neapolitans into his criminal organization. By the mid-1920s, Masseria was dominant in New York City. Underworld forces in New York, Chicago, Detroit and Cleveland supported Joe the Boss in his struggle against Salvatore D'Aquila and his many allies. Masseria officially became boss of bosses after D'Aquila's murder in 1928. The 1928 convention of Mafiosi in Cleveland, where much of Masseria's family resided, was likely held as a coronation of Masseria as the new supreme leader of the American Mafia. Among Masseria's chief advisers were former boss of bosses Giuseppe Morello and Saverio Pollaccia. Some believe Masseria briefly backed a return of Morello to the boss of bosses position in an effort to reunite the fractured Sicilian underworld in the U.S.
1930 - Gaspare Messina (Born Salemi, Sicily, Aug. 7, 1879. Died June 1957.). Messina appears to have entered the U.S. through New York City and to have lived in Brooklyn for a time before moving on to Boston. A son Salvatore was born in Brooklyn to Messina and his wife Francesca Riggio Messina in January of 1911. He moved to Boston before 1918 (perhaps as one of the D'Aquila men inserted into crime families across the country - though he later showed considerable independence from D'Aquila) and served as a Boston-based Mafia boss through much of the Prohibition Era. A dispute with Castellammarese Mafiosi in New York, Buffalo and the Midwest cost Giuseppe Masseria the confidence of the American Mafia membership. While the Mafia attempted to resolve the problem, Messina served as temporary boss of bosses. It is possible that Messina was no longer a boss of the Mafia in the Boston area and that he resided in New York City during his brief reign as temporary boss of bosses.
1931 - Salvatore Maranzano (Born Castellammare del Golfo, Sicily, c. 1886. Killed New York City, Sept. 10, 1931). Beginning in the late 1920s, Maranzano led a Castellammarese Mafia insurrection against boss of bosses Giuseppe Masseria. Though there is no evidence that Maranzano was ever officially appointed to any rank higher than soldier within the Schiro clan, he became the New York City war leader of the Castellammarese in the U.S. and many other Mafiosi who opposed the tyrannical reign of Giuseppe Masseria, including D'Aquila loyalists from the Mineo Crime Family (Gambino). After the April 1931 assassination of Masseria, Salvatore Maranzano secured for himself the designation of boss of all bosses in the American Mafia. He made repeated demands of tribute from other Mafia families and plotted against those he considered his rivals. After Maranzano's September 1931 murder, the American Mafia decided to do away with the boss of bosses designation in favor of a dispute-arbitrating Commission.