Prior to the bulk loading of cement, it was shipped in bags in box cars. Many of this countries transcontinental highways, built in the 1920s were built this way.
In the 1935-1937 is when dedicated fleet of covered hoppers and cement bulk containers started showing up. NE Pennsylvania was the starting area. These dedicated cars had steep slope sheet - about 80 degrees - that provided easier self unloading of the dense cement. A retrofitted coal hopper - with 120 degree slope sheets - did not self unload very well. Much cement needed to be either vibrated out or manually assisted out of the cars. This why the retro cars did not catch on. The RRs bought the dedicated covered hoppers.
Distance shipped - every ton mile costs money. The closest suitable product will be the cheapest. You would only buy a premium product if you needed a premium product, but even then the closest will likely be the cheapest.
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