While waiting for the subway to arrive, I noticed this mysterious symbol between “PRINCE” and “ST.” This is not a mistake of any kind. All of the signs at the station had this little triangle, and whoever created these signs put a significant amount of effort in inserting it. (Just look at how it is tiled.) Obviously this was something important for the artist who created this mosaic sign. What could it mean? It could not be a dash. Firstly, a dash would be inappropriate for this context. Secondly, if it were meant as a dash, it would have been much easier to draw a straight line out of these square tiles (instead of a triangle).
(FYI: This is New York City.)