Oil played a major role in World War II strategy. The US had it; Germany and Japan didn't. Japan's early moves were dictated by the need to get at the oil of the Dutch East Indies. And it is said that a major reason for Hitler's worst blunder (to attack the USSR without neutralizing England) was the need to secure access to oil reserves in the Caucasus. Though it required rationing, the US provided 85% of Allied oil supplies.

Presumably that is the north end of the yard in Homewood, IL. One can see the electrified commuter tracks on the left (west) side. Illinois Central was later acquired by CN who still maintains the large yard and a locomotive facility and administrative offices in the area. Photographer Delano seems to have spent quite some time capturing images in the area.

"An oil train from the Southwest leaves an Illinois Central railyard for the Pennsylvania Rail Road to be sent on to the East." At the same time a coal train leaves the destination in the East, bound for the Illinois Central railyard.

I can't go on ... anymore, I can't remember the difference between a coefficient and a variable. The only constant was I wanted to take geometry.

Lengthy oil trains like this move through Chicago and Milwaukee today.

I have read that the boom in American & Canadian production from oil sands & fracking exceeds the pipeline capacity, so oil trains are rolling.

A big one passed as I was re-photographing a Shorpy scene, (Chicago: 1956) it took 10 or 15 minutes to go by.