A little search for my time frame (1934) and my geography (east coast) reveals the “Minerals Handbook of 1935” with statistics and facts like: a little less than half of the asphalt petroleum was refined on the east and Gulf coasts using foreign crude from Venezuela, Mexico, and Columbia. Ninety-three percent of the asphalt refined on the east coast was from foreign crude. So east coast refineries were served by which tank car lines?

A quote from that handbook: “The tonnage of asphalt (natural, byproduct, or petroleum) terminated by class I railroads in the United States increased 14.6 percent from 2,407,553 short tons in 1933 to 2,757,897 tons in 1934-according to statistics of the Interstate Commerce Commission. Eighty-four percent of the road oil sold in 1933 and 79 percent of that sold in 1934 came from four refining districts-the East coast district, the Indiana-Illinois-Kentucky district, the Oklahoma-Kansas-Missouri district and the California district.”

I bet many lines had insulated tank cars that carried asphalt.

Standard Oil of Indiana was advertising it:

https://books.google.com/books?id=3EAEAAAAMBAJ&pg=PA59&lpg=PA59&dq=asphalt+roads+1934&source=bl&ots=cA4wKCXS-o&sig=FywJrBLiYhFz-yCRd92W2Maw8yQ&hl=en&sa=X&ved=0ahUKEwjwzYPyqvfOAhUGLyYKHe9eAIgQ6AEIMDAD#v=onepage&q=asphalt%20roads%201934&f=false

What would a Standard Oil tank insulated tank car look like at that time?

Dave