It's always nice to use a link from the ultra-conservative CATO Institute that bashes Trump's wall
Why the Wall Wont Work
By David Bier
This article appeared in the May 2017 issue of Reason.
Donald Trump captured the imagination of many American voters with a single campaign promise. I will build a great, great wall on our southern border, he boasted in June 2015. For good measure, he added, And I will have Mexico pay for that wall. The twin pledges-which followed a tirade about Mexican rapists and drug dealers-neatly captured everything that was either attractive or repulsive to voters in the real estate moguls presidential run: bravado, nationalism, and controversy.
Trump was often criticized for lacking precision in policy ideas, but he had bold and detailed requirements for his wall. It would be 1,000 miles long. (The other 1,500, he said, were covered by natural barriers.) He gave various estimates of its height-between 30 and 50 feet, with the most common number being 35. His barrier would be an impenetrable physical wall composed of precast [concrete] plank
30 feet long, 40 feet long. He also insisted that it would be aesthetically pleasing.
While he said after the election that a fence may be appropriate in some areas, he added that a wall would be better, and he has since vigorously corrected reporters who describe the project as a fence. Throughout the campaign, he described the current fences as a joke, implying that he would not only build a superior barrier, but that he would replace the one that exists at some points now.
More: https://www.cato.org/publications/commentary/why-wall-wont-work