The Hall Signal Company was an American manufacturer of railway signaling equipment in the 19th and 20th centuries. Hall's equipment was widely used by American railroad companies. The company's founder, William Phillips Hall, was an inventor who developed several important devices in the history of railway signalling. The company manufactured automatic block signaling systems, disc signals (also called "banjo" signals), a rotating semaphore signal, grade crossing signals, and the first searchlight-style signal.