It's the Phone, Stupid: Mobiles and Murder

US homicide rates fell sharply in the early 1990s, a decade that also saw the mainstreaming of cell phones – a concurrence that may be more than a coincidence, we propose. Cell phones may have undercut turf-based street dealing, thus undermining drug-dealing profits of street gangs, entities known to engage in violent crime. Studying county-level data for the years 1970-2009 we find that the expansion of cellular phone service (as proxied by antenna-structure density) lowered homicide rates in the 1990s. Furthermore, effects were concentrated in urban counties; among Black or Hispanic males; and more gang/drug-associated homicides.