We need to be realists. You really dont think that a wall would do along the Rio Grande do you? Although not impossible, they would have to consider floods a all that, which weakens the foundations. Half that river is ours and there is no way possible to put the wall in the middle of that river.
Then comes the canyons and such.
Then comes the canyons and such.
Don't go all Spock on us! Getting all Logical and all!