Dripping from bridges, scrawled across alleyway walls and tagged on garbage cans along busy streets, graffiti brings color and gives voice to unheard perspectives in many parts of Washington, D.C.

In 2006, $5 million was spent on graffiti in Auckland, New Zealand, according to the New Zealand government's "How to Stop Graffiti Guide." If graffiti wasn't a problem, New Zealand could have used ...