http://www.seedmagazine.com/news/2009/01/chaos_begets_chaos.php
Broken window theory (BWT), first proposed by James Wilson and George Kelling in 1982, holds that the presence of disorder – in the form of broken windows, litter, and graffiti – can encourage delinquent behavior. BWT promotes a “nip it in the bud” stance toward crime prevention: Fix small problems (like litter) before big problems (like theft) have a chance to occur. Former New York City mayor Rudy Giuliani was a loyal subscriber to the theory. He focused on small-scale issues like graffiti, prostitution, and squeegee men to influence, and ultimately drive down, crime in a seemingly unmanageable city.
I first read about this in Malcolm Gladwell’s The Tipping Point, and the idea has impressed me ever since. The author’s citing Rudy Giuliani’s efforts, though, humbles me – I remember thinking at the time that he was a bit of a tinpot dictator, but the huge drop in NYC’s crime rate proves he was on the right track there, at least.