is a place where the unexpected becomes expected,where radical change is more than possibility. It is—contrary to all our expectations—a certainty.
In pursuit of this radical idea, I’m going to take you to Baltimore, to learn from the epidemic of syphilis in that city. I’m going to introduce three fascinating kinds of people I call Mavens, Connectors, and Salesmen, who play a critical role in the word of mouth epidemics that dictate our tastes and trends and fashions. I’ll take you to the set of the children’s shows Sesame Street and Blue’s Clues and into the fascinating world of the man who helped to create the Columbia Record Club to look at how messages can be structured to have the maximum possible impact on all their audience. I’ll take you to a high tech company in Delaware to talk about the Tipping Points that govern group life and to the subways of New York City to understand how the crime epidemic was brought to an end there. The point of all of this is to answer two simple questions that lie at the heart of what we would all like to accomplish as educators, parents, marketers, business people, and policymakers. Why is it that some ideas or behaviors or products start epidemics and others don’t? And what can we do to deliberately start and control positive epidemics of our own?
ONE
The Three Rules of Epidemics
In the mid 1990s, the city of Baltimore was attacked by an epidemic of syphilis. In the space of a year, from 1995 to 1996, the number of children born with the disease increased by 500 percent. If you look at Baltimore’s syphilis rates on a graph, the line runs straight for years and then, when it hits 1995, rises almost at a right angle.
What caused Baltimore’s syphilis problem to tip? According to the Centers for Disease Control, the problem was crack cocaine. Crack is known to cause a dramatic increase in the kind of risky sexual behavior that leads to the spread of things like HIV and syphilis. It brings far more people into poor areas to buy drugs, which then increases the likelihood that they will take an infection home with them to their own neighborhood. It changes the patterns of social connections between neighborhoods. Crack, the CDC said, was the little push that the syphilis problem needed to turn into a raging epidemic.
John Zenilman of Johns Hopkins University in Baltimore, an expert on sexually transmitted diseases, has another explanation: the breakdown of medical services in the city’s poorest neighborhoods. “In 1990–91, we had thirty six thousand patient visits at the city’s sexually transmitted disease clinics,” Zenilman says. “Then the city decided to gradually cut back because of budgetary problems. The number of clinicians [medical personnel] went from seventeen to ten. The number of physicians went from three to essentially nobody. Patient visits dropped to twenty one thousand. There also was a similar drop in the amount of field outreach staff. There was a lot of politics—things that used to happen, like computer upgrades, didn’t happen. It was a worst case scenario of city bureaucracy not functioning. They would run out of drugs.”
When there were 36,000 patient visits a year in the STD clinics of Baltimore’s inner city, in other words, the disease was kept in equilibrium. At some point between 36,000 and 21,000 patient visits a year, according to Zenilman, the disease erupted. It began spilling out of the inner city, up the streets and highways that connect those neighborhoods to the rest of the city. Suddenly, people who might have been infectious for a week before getting treated were now going around infecting others for two or three or four weeks before they got cured. The breakdown in treatment made syphilis a much bigger issue than it had been before.
There is a third theory, which belongs to John Potterat, one of the country’s leading epidemiologists. His culprits are the physical changes in those years affecting East and West Baltimore, the heavily depressed neighborhoods on either side of Baltimore’s downtown, where the syphilis problem was centered. In the mid 1990s, he points out, the city of Baltimore embarked on a highly publicized policy of dynamiting the old 1960s style public housing high rises in East and West Baltimore. Two of the most publicized demolitions—Lexington Terrace in West Baltimore and Lafayette Courts in East Baltimore—were huge projects, housing hundreds of families, that served as centers for crime and infectious disease. At the same time, people began