We’ve come to expect to see graffiti in alleyways, on the sides of buses, on schools, even on people themselves—in short, in Anywhere, Urban America. Where we don’t expect to see vandalism is up in the high country or in our national forests or parks. But guess what: Graffiti artists are moving in.
http://www.backpacker.com/graffiti_parks/blogs/daily_dirt/1505