Vertical organizations, flat networks: Centrality and criminal collaboration in the Italian-American Mafia

•We analyze a historical network of criminal collaboration across 24 Italian-American Mafia families.•Ties were more prevalent among mafiosi with similar centrality-based status than among status-dissimilar mafiosi.•Informal centrality-based status mattered more for collaboration than did a mafioso’s formal position in the organization.•Knowledge of “on-the-ground” patterns of interaction is vital for understanding the structure of organizations.