It sounds like BS to me that a wall is so expensive, look at a damn interstate highway with overpasses, bridges, cloverleafs, earthwork, tunnels, and on and on. It ought to be obvious to everyone that the interstate, and all other major highways would cost many times per mile what a wall would cost, and never in my life have I ever heard that we can't afford to build a highway. I wonder what they all add up to 100s of thousands of miles I reckon.
That wall is like building all those highways before cars were invented.
