I was referring primarily to the volunteer homeless, not the mentally ill. The bums of the world, the riders of the rails, the hobo of yesteryear.
My grandfather use to regale me with tails of his years as a hobo (back in the early part of the 20th century). Wish he had written them down, would make for a great read. ;-)
i spent some time wandering in the 70's myself, but by thumb never tried the rails