It used to cost the Chicago mass transit authority $20 million a year to clean up graffiti, or rude decorations, that people had spray-painted on subway cars, buses and station signs. Then the agency got smart. Instead of just chasing and prosecuting taggers, as graffiti artists are called, it began encouraging and rewarding them.
Wall scratching and unauthorized cave paintings go back to ancient Greece and Rome and beyond. And keeping one step ahead of the law while spray-painting messages such as "Freddie Loves Linda" or "Paco Was Here" is a thrill for today's taggers and their friends. But these painted flourishes infuriate property owners, offend many passersby and make a bus or a subway system or a neighborhood seem unsafe.
When Chicago transit police caught some of these graffiti artists, they found them to be decent kids who were just showing off. And since it cost a lot of time and money to take them to court, the agency chose 7 spots around Chicago, erected huge walls and said, "OK, kids, go at it."
It didn't stop all illegal tagging for sure, but it nurtured an entire community of legal artists who proudly show off their work on the street and online. Some of their work is even judged by experts, with paid commissions and scholarships to art academies as rewards.
Very few of the legal taggers have been arrested for vandalizing property elsewhere, and the approved walls are almost never defaced by illegal graffiti.
So in Chicago, and now in many other American communities as well, there's a place where you can go and spray "Paco Was Here" - not in the dead of night with one eye out for the cops, but in the middle of the day if you feel like it, with the police looking on, approvingly.
graffiti: drawing or inscription made on a wall or other surface, usually so as to be seen by the public（在墙壁等上面的涂抹乱写）
spray-paint：to cover, mark, draw, or write with spray paint（喷漆）
infuriate：to make furious; enrage（激怒）
deface：to mar the surface or appearance of; disfigure（丑化，损伤外观）