In the state of Oklahoma the county roads are designated with a number and a letter. E on roads extending east and west and S on roads extending north and south.Those roads traveling east and west are designated a number and the letter E. Those roads traveling north and south are designated with a number and an N. I under stand that the N represents that the road is north of the equator. What does the E stand for. I assume it means east of, but what is the East base point. I would guess that all E and W designations mean east or west of the prime meridian. That assumption on my part must be incorrect because in Oklahoma we are west of the prime meridian. I doubt that the international date line is what we are east of in Oklahoma when determining what the E stands for in our road numbering system. Also does the number mean " degrees from O degrees as N 2100 would mean 2100 degrees north of the equator?