The Greyhound bus system is more than just cheap transportation, it's an American institution. It is a symbol of freedom and at the same time a symbol of loneliness.
I traveled for an entire summer around the continental United States on a bus, and I know there is a lot more to it than just what's on the surface. A greyhound bus is a place where you'll meet psychos and evangelists, but it's also a place where you'll meet sailors going home to see their family while on shore leave. I met a Vietnam Vet who served two tours of duty as a demolition expert, and now is drinking to dull the pain of his arthritis because the government health care wouldn't cover the treatment he needed. I also met an entire family of five that was moving, with all their worldly possessions in the luggage compartment because the factory in their town had closed and they lost their house.
I met a man who was taking a two day bus ride to visit his wife who was an officer in the army and was stationed in Texas. He normally stayed at home with the kids while she was the breadwinner. I met a couple truckers who were on their return trips home after making a long haul one way delivery. I met people who were going home for the first time in years and people who were crossing the continent to see an old friend or a lover whom fate had moved far away.
There is something about the bus, the anonymity coexisting so starkly with the extreme individual humanity of the people, the constant flow of uprooted people, each an individual, but yet part of an endless tide. That freedom and that loneliness is part of the american spirit. Tom Waits captures the spirit well in the song Invitation to the Blues (although technically it's a Trailways bus in the song, the meaning is there). All I'm saying I guess is that the culture of the whole thing is pretty much a unique experience.