Giancana rose through Chicago's criminal underworld to lead one of the most powerful organized crime organizations in the United States, wielding influence that extended from street-level gambling operations to the highest levels of American politics and government. His tenure as boss of the Chicago Outfit brought him into contact with both a presidential campaign and a CIA assassination plot — a reach that distinguished him from the ordinary machinery of organized crime. The breadth of his documented connections, legitimate and otherwise, made him a figure whose full significance remained contested long after his own violent death in 1975.