
Several decades ago graffiti was invented in NYC's South Bronx, and was initially more about defacement and outcries of social injustice than the art form it later evolved into.

Japan imported the concept, and has unsurprisingly evolved it into something else entirely. Check out Pink Tentacle's insanely thorough photo gallery of painted trains in Japan.
Comments
Graffiti was 'invented' in NYC?? Come off it, it has been and will be around for centuries!! http://en.wikipedia.org/wiki/Graffitti
I wouldn't reference wikipedia to prove a point, but yes, graffiti has been around for a while. I think the oldest known example was an anti-Christian insult from ancient Rome. The more things change...
I wish the subway trains still looked like they did then...