According to the "Guide to Gasoline Logos" ; Calso started in the late 1930's in the Rocky Mtn states & in the Northeast states in 1945-46 & logo/sign was used in 1940-41.

Pictured map is a 1939 with the marketing area in the 2nd picture.

Dave

Calso GA 1939.jpg Calson Marketing area 1939.jpg