I know little of car pools and am maybe oversimplifying things. My definition of a pool would be: Railroad X buys freight cars to carry an industries product. That industry loads and sends the cars indecrimitly with the cars returning for another load when empty.
I'm sure to find out how this really works.
Back when 5 railroads served Mason City the local cement plants ran a pool arrangement for box cars. If they were to ship 11 loads out on your RR then you were to supply them with 11 empties. You probably would not get the same cars back loaded you gave them empty. Most box cars in photos do not belong to the 5 local roads, lots of PRR cars. Although I have records of lots of CGW X29 style (Ted says AAR cars) with cement loads on the M&StL. Today the plants are still protected by a covered hopper pool. I'm told it's one of the every few still around.
