There is a nice geospatial connection here. As with many epidemiological issues, spatial locality is an important aspect of the analyses that lead (ahem) to the conclusion. The article is chock-full of references to the spatial nature of the problem, such as:
We now have studies at the international level, the national level, the state level, the city level, and even the individual leveland my favourite:
a good rule of thumb for categorizing epidemics: If it spreads along lines of communication, he says, the cause is information. Think Bieber Fever. If it travels along major transportation routes, the cause is microbial. Think influenza. If it spreads out like a fan, the cause is an insect. Think malaria. But if it's everywhere, all at once—as both the rise of crime in the '60s and '70s and the fall of crime in the '90s seemed to be—the cause is a molecule.