Roadway used the numerical system as a designation for geographic parts of the country. For example: terminal 135, Harrisburg, Pa, terminal 187, Brooklyn, NY. Generally speaking, a 100 code would be the North East. Each region of the country was divided up this way. Now, on the dock, all loads are loaded by code designation to go to a specific destination (break bulk) How it helps: if I don't have enough 457 freight (Meridian, MS) I know that I can load any 500 destination (all of Texas) 0r any 800 destination (the whole west coast) on the back of that trailer to keep the freight moving. And, on our dock, all of these doors load in the same area, so I don't have to run all over to get freight. From my perspective, I don't have to look at the city address. I only need to use the destination code on the waybill.