Daryl LaFleur links to this valuable Economist article in Northampton Redoubt:

Can the can: The idea that graffiti-spraying and other forms of low-level delinquency promote further bad behaviour has now been tested experimentally (11/20/08)

A place that is covered in graffiti and festooned with rubbish makes people feel uneasy. And with good reason, according to a group of researchers in the Netherlands. Kees Keizer and his colleagues at the University of Groningen deliberately created such settings as a part of a series of experiments designed to discover if signs of vandalism, litter and low-level lawbreaking could change the way people behave. They found that they could, by a lot: doubling the number who are prepared to litter and steal...

The researchers’ conclusion is that one example of disorder, like graffiti or littering, can indeed encourage another, like stealing. Dr Kelling was right. The message for policymakers and police officers is that clearing up graffiti or littering promptly could help fight the spread of crime.

See also:

New Blog: Northampton Blight
"Every city faces the challenge of keeping things well maintained and looking good, but Northampton has been looking pretty darn shabby lately. And there doesn’t appear to be much interest by our city officials in restoring the beauty of just a few years ago..."

We are reminded of the UK website Love Lewisham, where citizens can report problems like stray trash to the municipal council. We wish Northampton Blight well.

SeeClickFix
Create a public record of something that is wrong and can be fixed. Examples include potholes, graffiti, litter or needed traffic signage.

The Atlantic: "Broken Windows"
...at the community level, disorder and crime are usually inextricably linked, in a kind of developmental sequence. Social psychologists and police officers tend to agree that if a window in a building is broken and is left unrepaired, all the rest of the windows will soon be broken. This is as true in nice neighborhoods as in rundown ones. Window-breaking does not necessarily occur on a large scale because some areas are inhabited by determined window-breakers whereas others are populated by window-lovers; rather, one unrepaired broken window is a signal that no one cares, and so breaking more windows costs nothing. (It has always been fun.)

...In Boston public housing projects, the greatest fear was expressed by persons living in the buildings where disorderliness and incivility, not crime, were the greatest. Knowing this helps one understand the significance of such otherwise harmless displays as subway graffiti. As Nathan Glazer has written, "the proliferation of graffiti, even when not obscene, confronts the subway rider with the inescapable knowledge that the environment he must endure for an hour or more a day is uncontrolled and uncontrollable, and that anyone can invade it to do whatever damage and mischief the mind suggests."

Graffiti Hurts
Immediate removal - within 24-48 hours - is the key to successful graffiti prevention.

NoGraf Network

Berkeley Police Department: "What Is Graffiti About?" (PDF)

Times-Picayune: "Vandalism or art? Struggle between graffiti producers and those who seek to prevent it has flared again"
"I don't think graffiti spread all around makes people feel comfortable or gives a sense of pride," Ligi said. "Especially after Katrina. We've worked so hard to bring it back. We have to have zero tolerance."