Mysterious dirt roads can been seen when flying into El Paso Airport.?

I have flown into El Paso, TX airport many times. As you approach from the East it looks like many square miles of neighborhood roads have been graded in the desert. There is no pavement, but you can clearly see the layout of streets, intersections and cul-de-sacs. Does anyone know what these roads are for? Was this some great plan to expand El Paso that never materialized?