During the nearly three decades that heroin was legal, hundreds of thousands of Americans from all walks of life who used the drug for pain relief and other medicinal purposes developed addictions to it. By the time the drug was made illegal in 1924, the majority of the nation's heroin addicts had relocated to the inner city to gain access to government-sponsored free-heroin clinics.

The majority of the nation's heroin use remained confined to the inner city for decades after the drug's illegalization. Because it was out of the view of mainstream America, society would come to underestimate the drug's potential for widespread addiction until epidemics of heroin use during the 1960s and 1990s showed the drug's alarming universal appeal.

Like the physicians of ancient societies, who believed that heroin's parent drug, opium, was a sacred panacea (cure-all) provided by the...