If you live in a city and walk alone at night, you probably prefer routes that are well-lit over ones that aren't. The same surely holds true even if you live in a more suburban area. Associating light with safety is one of those feelings that's so universal, I can almost hear the entire planet rolling its eyes in collective irritation right now.
But what if extra lighting doesn't actually make us safer?
After the London borough of Wandsworth installed 3,500 new street lights in the mid-1980s as part of its overall crime reduction plan, researchers at the University of Southampton decide to compare reported crimes before and after the upgrade. Despite the fact that increased lighting had been a mainstay of city crime prevention for decades, the researchers found "no evidence ... to support the hypothesis that improved street lighting reduces reported crime."
Cities in the U.S. attempted similar experiments during the same period of time, and got mixed results. According to a 2007 systematic review of lighting experiments in American cities, increased street lighting in Indianapolis, Harrisburg, New Orleans, and Portland, Oregon, did not coincide with a drop in the affected areas' crime rates, but it did in Atlanta, Milwaukee, Kansas City, and Fort Worth. Yet even in U.S. cities where lights "worked," they didn't appear to work consistently: While Fort Worth saw a decrease in all types of crime, Kansas City saw a decrease only in violent crime.
But here's something that will really throw you for a loop: Street lights enable criminals as much as they do their potential victims, according to criminologist Ken Pease. With increased street-lighting, potential thieves have an easier time seeing the contents of parked cars, don't need to carry flashlights (which could alert someone to their presence), and are able to case a place and determine if there's anyone around who can impede their break-in. The light may scare criminals away, but it can also tell them enough about a house or a street or a parking lot to know whether there's anything for them to be scared of.
So what happens when you take away lights? A recent study conducted in Chicago on behalf of the Chicago Department of Transportation found that street light outages have different effects on different neighborhoods. "For some of the community areas, there were not enough crimes in outage-affected areas to estimate the model," the authors said. Other neighborhoods, meanwhile, saw crime rates increase as much as 134 percent when street lights were out. Intentional efforts to reduce light pollution (as opposed to outages) have been conducted across the U.S. and Europe without corresponding crime increases; except possibly for Oakland, where an energy-efficient lighting ordinance passed in 2002 was blamed for a homicide spike in 2011.
The connection between light and crime may not be what most of us think it is, but the connection between light and our sense of safety is exactly what it's always been. Those Southampton researchers who measured crime rates in Wandsworth also found that the new lights "provide[d] reassurance to some people who were fearful in their use of public space," particularly women. Lighting increases a sense of community, and community pride. It brings us outdoors in our neighborhoods, helps us get to know each other. Fear keeps us out of the alley, and attraction to light and what it represents draws us to illuminated streets.