Abstract: A foldable road marker is formed of a pair of panels each having a central stem portion integrally connected with side panel portions. The panels each having an elongated slot with the stem portion and slots being coaxial. Each stem portion is fitted within the slot of the opposite panel for interconnecting the panels. The panels are pivotable relative to each other into a position in which they are transverse to each other or, alternatively, into a folded position in which they are generally parallel and closely overlap to each other for storage. Guide members are formed in the slots of each of the panels for slideably fitting within vertically arranged guide channels formed in the stem portions of their opposite panel for guiding the assembly of, and the positions of, the panels relative to each other. Detents are provided for holding the panels in their transverse position for marker use or, alternatively, in their folded, parallel storage position.