I was sorry to see the previous discussion started by Tom_Consulting shut down because it got to be a political discussion. But in answer to the original question, here is one technical challenge to overcome: If the earth curves at 8" per mile x the distance squared, then over the 1954 miles of border between the US and Mexico there will be over 482 miles of curve to compensate for. In other words if you built a wall dead level over the entire length with the starting point tangent to the surface, the other end of the wall would be 482 miles above the surface of the earth, lol. Kind of makes you wonder about the salt flats in Bolivia that 280 long and dead flat and about the 1000 mile long railway in Australia that is dead level, straight and true over the entire length. Or most bewildering to me: the Nile river starts at an elevation of 3721' and drains at sea "level" 4180 miles later, I am confused how it deals with over 2206 miles of curvature. These are facts, what are your thoughts on this?
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