Depew Depot at Niagara Junction New York Lehigh Valley Railroad Real Photo Postcard

An interlocking tower, a crucial element of railway safety and efficiency during the late 19th and early 20th centuries, managed complex mechanical or electro-pneumatic systems. These structures enabled a signalman to control multiple switches and signals across a railway junction or a designated stretch of track, preventing collisions and expediting train movements. The presence of multi-arm semaphore signals further indicates a period before the widespread adoption of modern color-light signaling.