Calling All Cars was a radio show that was first broadcast in 1933. The image above shows a panel from a 1939 road map distributed by the show’s sponsor.
“Every week a dramatization based on an actual police case file was… introduced by a real police officer… Sponsored by the Rio Grande Oil Company… [it] aired only along the West Coast, restricted to only the territory where the sponsor’s product was distributed… [T]here was evidence that the weekly detective program was the most popular originating from the West Coast facilities of CBS… Commercially, the program was a huge success. In 1938 Parker Brothers issued a board game based on the radio program…
“Calling All Cars expanded to the Midwest beginning in January of 1939…”
Excerpts and image from http://martingrams.blogspot.com/2016/05/calling-all-cars-radio-program.html .
There is much more to the story of the show — read all about it at the link.
Listen to the actual shows at https://archive.org/details/OTRR_Calling_All_Cars_Singles .