What device first appeared in taxicabs in the late 1940s to improve dispatching?

The device that first appeared in taxicabs in the late 1940s to improve dispatching was the two-way radio.

Two-way radio transformed taxi work by allowing drivers and dispatch offices to communicate directly. A dispatcher could relay a passenger request to a cab, while drivers could report their locations and availability without returning to a stand or stopping at a telephone.

Before radio dispatch became common, many taxi systems relied on callboxes: special telephones installed at taxi stands or strategic locations. That method was slower and tied drivers to fixed points. Radio made fleet coordination more flexible and helped companies serve telephone bookings more efficiently.

Modern dispatching has added computers, GPS, mobile data terminals and smartphone apps, but the basic idea remains similar: match a passenger with an available vehicle. A roof light identifies availability, while a GPS receiver helps track location; neither device was the key late-1940s dispatch innovation.