Long Straight line roughly 2 miles east of interstate 40 in Arizona?

I was flying from New Mexico to California the other day and noticed a long straight line in the earth that almost looked like a natural "border" line. It seemed quite wide and man made. It also appeared to be completely dry and empty (so not a canal of some kind). I found it on google maps here:
https://maps.google.com/?ll=35.02107,-114.084971&spn=0.01151,0.019891&t=h&z=16

It looks like they have labeled it as something... but it sure looked empty.
Any ideas? (It seems to continue indefinitetly. later on (north east) there are 2 such lines near the 40.

Thanks!
This is supposed to be in the Geography forum... but I think I made a mistake.