The face of heroin use in America has changed utterly. Forty or fifty years ago heroin addicts were overwhelmingly male, disproportionately black, and very young. Most came from poor inner-city neighbourhoods. These days, the average user looks different. More than half are women, and 90% are white. The drug has crept into the suburbs and the middle classes. And although users are still mainly young, the age of initiation has risen: most first-timers are in their mid-20s. The spread of heroin to a new market of relatively affluent, suburban whites has allowed the drug to make a comeback, after decades of decline.