I was looking at photos on the Library of Congress website and found these from Omaha with freight cars. Most were taken November 1938, but I think one is from 1941.
Unloading 'coal' (looks like cinders or gravel to me) - MP USRA gondola
Union Stock Yards - boxcars in the background
Grain elevators - CGW boxcars in the midground, SAL box in the background, and what is that on the side of the boxcar behind the RI locomotive in the foreground?
CGW boxcar close-up (too bad the photographer wasn't back a foot or so)
American Smelting and Refining - nice cut of freight cars across the middle of the photo, is that a pickle car in the middle? Two rail cranes in the photo too.
Another view of American Smelting, but the freight cars are more distant
Unloading sheep at the stock yards - MILW stock car being unloaded, Quaker City Live Stock Express stock car in the background with part of a RI stock car.
Close-up of sheep being loaded into a stock car
Stock yards - decent view of ARLX 11801 on the right
Omaha rail yard - good views of roofs and ends
Omaha elevated view - some freight cars in the lower left corner