host: alan gomez, how much of a fence actually exists?t: right now, the last check is about 650 miles of fencing along the border. where you see mostly is in the very highly populated areas. example, san diego county sheriff bill gore has explained to me this idea that the fence -- where they determine where they need a fence has to do with assimilation. how quickly can summary cross illegally into the united states and assimilate into the general population? in a place like san diego, you absolutely need a fence because back in the 1980's, you could run from tijuana into san diego, and it would take you a matter of minutes to blend in with the local populace. somewhere in the middle of the desert, maybe not so easy. what they're saying is where they have been fence is now a very highly populated areas like san diego, yuma, southwest arizona, some of the border towns along texas that yes, it is absolutely valuable, it helps in those areas, but once you start getting into the desert, what you see is maybe some posts with little barb wire i