Cocaine had never been a big seller in the ghetto: it was too expensive. But that was before the invention of crack. This new product was ideal for a low-income, street-level customer. Because it required such a tiny amount of pure cocaine, one hit of crack cost only a few dollars. Its powerful high reached the brain in just a few seconds—and then faded fast, sending the user back for more. From the outset, crack was bound to be a huge success.

And who better to sell it than the thousands of junior members of all those street gangs like the Black Gangster Disciple Nation? The gangs already owned the territory—real estate was, in essence, their core business—and they were suitably menacing to keep customers from even thinking about ripping them off. Suddenly the urban street gang evolved from a club for wayward teenagers into a true commercial enterprise.

The gang also presented an opportunity for longtime employment. Before crack, it was just about impossible to earn a living in a street gang. When it was time for a gangster to start supporting a family, he would have to quit. There was no such thing as a thirty-year-old gangster: he was either working a legitimate job, dead, or in prison. But with crack, there was real money to be made. Instead of moving on and making way for the younger gangsters to ascend, the veterans stayed put. This was happening just as the old-fashioned sort of lifetime jobs—factory jobs especially—were disappearing. In the past, a semi-skilled black man in Chicago could earn a decent wage working in a factory. With that option narrowing, crack dealing looked even better. How hard could it be? The stuff was so addictive that a fool could sell it.

Who cared if the crack game was a tournament that only a few of them could possibly win? Who cared if it was so dangerous—standing out there on a corner, selling it as fast and anonymously as McDonald’s sells hamburgers, not knowing any of your customers, wondering who might be coming to arrest or rob or kill you? Who cared if your product got twelve-year-olds and grandmothers and preachers so addicted that they stopped thinking about anything except their next hit? Who cared if crack killed the neighborhood?

For black Americans, the four decades between World War II and the crack boom had been marked by steady and often dramatic improvement. Particularly since the civil rights legislation of the mid-1960s, the telltale signs of societal progress had finally taken root among black Americans. The black-white income gap was shrinking. So was the gap between black children’s test scores and those of white children. Perhaps the most heartening gain had been in infant mortality. As late as 1964, a black infant was twice as likely to die as a white infant, often of a cause as basic as diarrhea or pneumonia. With segregated hospitals, many black patients received what amounted to Third World care. But that changed when the federal government ordered the hospitals to be desegregated: within just seven years, the black infant mortality rate had been cut in half. By the 1980s, virtually every facet of life was improving for black Americans, and the progress showed no sign of stopping.

Then came crack.

While crack use was hardly a black-only phenomenon, it hit black neighborhoods much harder than most. The evidence can be seen by measuring the same indicators of societal progress cited above. After decades of decline, black infant mortality began to soar in the 1980s, as did the rate of low-birthweight babies and parent abandonment. The gap between black and white schoolchildren widened. The number of blacks sent to prison tripled. Crack was so dramatically destructive that if its effect is averaged for all black Americans, not just crack users and their families, you will see that the group’s postwar progress was not only stopped cold but was often knocked as much as ten years backward. Black Americans were hurt more by crack cocaine than by any other single cause since Jim Crow.

And then there was the crime. Within a five-year period, the homicide rate among young urban blacks quadrupled. Suddenly it was just as dangerous to live in parts of Chicago or St. Louis or Los Angeles as it was to live in Bogotá.

The violence associated with the crack boom was various and relentless. It coincided with an even broader American crime wave that had been building for two decades. Although the rise of this crime wave long predated crack, the trend was so exacerbated by crack that criminologists got downright apocalyptic in their predictions. James Alan Fox, perhaps the most widely quoted crime expert in the popular press, warned of a coming “bloodbath” of youth violence.

But Fox and the other purveyors of conventional wisdom were wrong. The bloodbath did not materialize. The crime rate in fact began to fall—so unexpectedly and dramatically and thoroughly that now, from the distance of several years, it is almost hard to recall the crushing grip of that crime wave.

Why did it fall?

For a few reasons, but one of them more surprising than the rest. Oscar Danilo Blandon, the so-called Johnny Appleseed of Crack, may have been the instigator of one ripple effect, in which by his actions a single person inadvertently causes an ocean of despair. But unbeknownst to just about everybody, another remarkably powerful ripple effect—this one moving in the opposite direction—had just come into play.

In Levitt’s abortion paper, published in 2001, he and his co-author John Donohue warned that their findings “should not be misinterpreted as either an endorsement of abortion or a call for intervention by the state in the fertility decisions of women.” They even suggested that crime might just as easily be curbed by “providing better environments for those children at greatest risk for future crime.”

Still, the very topic managed to offend just about everyone. Conservatives were enraged that abortion could be construed as a crime-fighting tool. Liberals were aghast that poor and black women were singled out. Economists grumbled that Levitt’s methodology was not sound. As the media gorged on the abortion-crime story, Levitt came under direct assault. He was called an ideologue (by conservatives and liberals alike), a eugenicist, a racist, and downright evil.

In reality, he seems to be very much none of those. He has little taste for politics and even less for moralizing. He is genial, low-key and unflappable, confident but not cocky. He speaks with a considerable lisp. His appearance is High Nerd: a plaid button-down shirt, nondescript khakis and a braided belt, brown sensible shoes. His pocket calendar is branded with the National Bureau of Economic Research logo. “I wish he would get more than three haircuts a year,” says his wife, Jeannette, “and that he wasn’t still wearing the same glasses he got fifteen years ago, which weren’t even in fashion then.” He was a good golfer in high school but has so physically atrophied that he calls himself “the weakest human being alive” and asks Jeannette to open jars around the house.

There is nothing in his appearance or manner, in other words, that suggests a flamethrower.

—THE NEW YORK TIMES MAGAZINE, AUGUST 3, 2003