From In Search of the American Hobo:

City life is interesting but full of danger. … The flophouse and the cheap hotel compel promiscuity, but do not encourage intimacy or neighborliness. On the outskirts of cities, however, the homeless men have established social centers that they call “jungles,” places where the hobos congregate to pass their leisure time outside the urban centers. […]

While often viewed as the haven in which hobo law, lore and tradition were passed on, the jungle could also be a place of danger and intimidation. Police, railroad bulls and criminals could find scapegoats or easy targets in the jungle congregation.

On all counts, the good and bad, the jungle was the place where “the fledgling learns to behave like an old timer,” where the “slang… and the cant of the tramp class is circulated” and where the “stories and songs current among the men of the road, the sentiments, the attitudes, and the philosophy” of the migratory laborer are aired and passed on.6

As the railroad carried the hobo from the jungles to the cities and back again, it also carried the slang, stories, songs and sentiments that were the heart of hobo culture.

Also very good, see: Hobo Chronicles.