First of a three-part series in the LA Times about retailing black tar heroin in the US.

Immigrants from an obscure corner of Mexico are changing heroin use in many parts of America.

Farm boys from a tiny county that once depended on sugar cane have perfected an ingenious business model for selling a semi-processed form of Mexican heroin known as black tar.

Using convenient delivery by car and aggressive marketing, they have moved into cities and small towns across the United States, often creating demand for heroin where there was little or none. In many of those places, authorities report increases in overdoses and deaths.

Immigrants from Xalisco in the Pacific Coast state of Nayarit, Mexico, they have brought an audacious entrepreneurial spirit to the heroin trade. Their success stems from both their product, which is cheaper and more potent than Colombian heroin, and their business model, which places a premium on customer convenience and satisfaction.

Users need not venture into dangerous neighborhoods for their fix. Instead, they phone in their orders and drivers take the drug to them. Crew bosses sometimes call users after a delivery to check on the quality of service. They encourage users to bring in new customers, rewarding them with free heroin if they do.