Urban planners may cry “bring us a shrubbery” to deter crime

Philadelphia's more vegetated areas tend to have less crime, new research has found

Terry Robinson

One school of thought has it that inner-city trees and shrubs make convenient hiding places and covered escape routes for criminals. Another, supported by an increasing body of evidence, argues that urban foliage may actually reduce crime. Where previous studies have tended to focus on individual housing blocks or, at best, neighborhoods, new research out of Temple University is among the first to examine the issue at the city-scale. TU researchers analyzed the relationship between vegetation concentration and crime for the whole of Philadelphia.

The researchers broke the city down into 363 "tracts" identified from socioeconomic census data, each containing between 100 and 8,000 people. The data, taken from the years 2005 to 2009, was also used to assess poverty and education levels in these tracts. Vegetation coverage was assessed from satellite imagery from 2005, courtesy of NASA's Landsat 7. Recorded incidents of aggravated assault, robbery, burglary, and theft were drawn from the University of Pennsylvania's Neighborhood Information System CrimeBase, also for the year 2005.

Theft, just to be clear, is the illegal act of taking something without permission. Robbery is the same, but with violence (or the threat of it). Burglary is breaking into a building in order to a commit crime (often, but not necessarily, theft or robbery.) The researchers ignored incidents of murder and rape on the grounds that their relative rarity renders the comparison senseless at tract level.