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The Sinaloa cartel from Mexico "has overtaken Colombian and Asian drug suppliers in New York, and that cartel now dominates heroin distribution across the United States" as reported by Sylvia Longmire for Breitbart News.
Eighty percent of the illicit drugs -- heroin, cocaine, methamphetamine and marijuana -- in Chicago, IL are supplied from Mexico by the Sinaloa cartel which was headed by Forbes-listed billionaire Joaqin "El Chapo" Guzman until his recent arrest, and the Windy City is used as its hub for further distribution throughout the Midwest and country as reported last year by Jason McGahon for Chicago Magazine.
Further reading that may be of interest: