Short answers, pulled from the story.
Giuseppe Esposito became the first known Mafia member to immigrate to the United States in 1881. Police arrested him in New Orleans before sending him back to Italy.
On the 14th of March 1891, angry citizens formed a lynch mob that killed eleven of nineteen Sicilian defendants. Two were hanged while nine were shot following an acquittal for the murder of Superintendent David Hennessy.
Prohibition allowed criminal gangs to make fortunes by shipping over 900,000 cases of liquor into U.S. cities from Canada and the Caribbean. Gangs hijacked shipments and waged wars for control over bootlegging rackets during this period.
Salvatore Maranzano created the modern organizational structure in 1931 after Charles Lucky Luciano orchestrated his murder within six months. Each crime family had a boss, underboss, capos, soldiers, and made men who required permission for harm.
Joe Valachi became the first Mafia member to turn state evidence in 1963 when he testified before Senator John L. McClellan's Permanent Subcommittee on Investigations. His televised testimony exposed American organized crime to the world and broke his blood oath known as omertà.