Richard
I'd hazard a guess that you might be seeing power line routes. From 35,000 feet or so you might not see the line itself but the cleared corridor and tracks made by construction and maintenance vehicles. Could you find them on Google Earth or Bing Maps? I found a few and they appear to run to industrial plants, probably associated with mining, oil etc.
Typical corridor (found at random on Bing Maps):
In this case I think it's two power lines side by side and the resulting cleared area, about 500' wide has been used for agriculture.