Most Americans are quite insulated from trains. Seeing one, at least in the Midwest, is an oddity. I, on the other hand, live right along the major rail line between St. Paul and Seattle and so I see a lot of trains and I see a lot of graffiti.
When people from the States go to Europe they often ride trains, perhaps for the first time in their lives, and certainly more than most people from the States ever use trains at home. They are shocked at the level of graffiti in train stations and along train lines. And the idea of Americans is further strengthened by the fact that graffiti is considered a crime in many communities.
What they don't know is that we have a lot of graffiti too associated with trains. Last Sunday I walked up to the scientific garden maintained by the Science Museum. That put my right along the train track, rather than across the road and up in my apartment. Thus I had a good opportunity to take some photos of American graffiti.