As you’ve traveled around the Commonwealth, you may have noticed a few areas that seem to have an odd bit of graffiti. Instead of profanity or expressions of despair, these little white painted spots on walls, overpasses, and other surfaces seem to have purpose. But what? Simple answer: they are used by the Railroad to communicate and leave messages behind for other agents in the faction.
You may have not reached that part of the game yet, but that doesn’t mean you can’t benefit from knowing what these little white symbols and markers mean. Above is a chart from within the Railroad headquarters. As you can see, each symbol is surrounding by a burst of white lines radiating out from the center. The plus sign denotes the location of an ally, while the square reveals the hiding spot of a cache. The X marks danger, like an area with multiple enemies. The pointer leads you to another spot, often a cache or ally. The symbol of a house predictably reveals a safehouse for Railroad member use. And the teardrop means the location is used as a dead drop for secret missions. Use the symbols wisely!