"What we know about hobo graffiti comes from hobos — a group that took pride in embellishing stories.
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Hobos, or tramps, were itinerant workers and wanderers who, beginning in the late 19th century, illegally hopped freight cars on the then-expanding railroad in the United States. They used graffiti, or tramp writing, as a messaging system to tell their fellow travelers where they were and where they were headed next. Hobos would scratch or draw their road persona, or moniker, onto stationary objects near railroad tracks like water towers and bridges. News stories at the time, largely informed by hobos themselves, spread tales of a different kind of graffiti though. One that included coded symbols that supposedly drawn on fence posts and houses to convey simple messages to tramps about if that home or town. While this language probably existed on some level, it certainly was not as widespread as media of the time would have readers believe, and hobos as a source would have no reason to be fully truthful about the use of the symbols. Freight graffiti and monikers eventually expanded to include rail workers, who would draw their monikers on the boxcars coming through train yards."