very huge thunderstorms, hoouch volumehugevolumes of water coming through here. they have a strand of barbed wire between the u.s. and mexico. very easy to go over but this. this is where the ruggedness and the remoteness of the terrain does job for you. but experts say perhaps the strongest argument against a wall is that it doesn't address the biggest part of the illegal immigration problem. and that's because the majorities of people who make it into the country illegally do it right through ports of entry. they hide in vehicles or they use forged documents. so here it is. is it even possible for trump to build his great wall, whatever he would call it? well as we've seen probably not. would it even make much of a difference? that certainly isn't clear. the only thing we know for sure is that it would cost an extraordinary amount of taxpayer money. >> and paul beban is back. he joins us now. paul it all comes down to economics for me. has trump said how woe pay for there wall? as you've demonstrated it would be more expensive than one we've got already. >> yes