[octex]

I think Dave was referring to the areas near Big Bend where the cliffs along the river are about 300 ft., not the areas closer to El Paso where there is easier access.

[Dave W]

That's what I wrote - west of Big Bend. El Paso is a different matter. You noticed how he wrote El Paso, who has some emotional issue with Texas and perhaps should move from the state.

Much of the land west of El Paso is privately owned and some of those folks don't want a wall on their property. It will take a while to resolve those issues.