We examine the migration to the United States of Mafiosi fleeing Fascist repression in the 1920s. Using historical US administrative records containing the Sicilian municipality of birth matched with full censuses and FBI reports from decades later, we provide evidence that expelled mafiosi settled in pre-existing Sicilian immigrant enclaves and triggered the rise of the Italo-American Mafia. Our analysis reveals that 75% of future mafia leaders in the US originated from only 1.7% of neighborhoods that had hosted immigrant communities originating in the 32 Sicilian municipalities targeted by anti-mafia Fascist raids decades earlier. Future mafia activity is also disproportionately concentrated in these same neighborhoods. We then explore the socio-economic impact of organized crime on these communities. In the short term, we observe increased violence in adjacent neighborhoods, heightened incarceration rates, and redlining practices that restricted access to the formal financial sector. However, in the long run, these same neighborhoods exhibited higher levels of education, employment, and social mobility, challenging prevailing narratives about the purely detrimental effects of organized crime. Our findings contribute to debates on the persistence of criminal organizations and their broader economic and social consequences.