If you've ever used DeKalb Av station on the B/Q/R, you may have seen one of these illuminated boxes. Ever wondered how it works? Known as an Annunciator, this 20th-century analog tech relies on simple electric circuits on the tracks to give riders an advance heads up of the route of the next train. When train dispatchers set track switches in place, the corresponding route automatically illuminates. Predating countdown clocks by several decades, this simple yet helpful tool has stood the test of time and continues to operate alongside our modern countdown clocks. Let us know if you remember seeing annunciators at other stations in the past! 📸: @brendonc727