I find the idea of a wall to stop illegal immigration to be … beyond silly. As a military barricade — that is, to prevent large-scale movements across a border — it can be effective (it can also be completely INeffective, see: Maginot Line). But if there were thousands of people marching across the Mexican/Texan desert, we could watch for heat signatures & deploy border patrol to intercept. Illegal immigration won’t look like a Mongol army marching across the steppes.
Reviewing walls that have been erected throughout history, the only truly effective method to prevent small scale involves a lot of manpower and a dead-zone. The fourth generation Berlin Wall is a good example of an effective stop to emmigration. But it had over 100 watchtowers in less than 100 miles and several bunkers housing the troops who guarded the wall. There were also two walls with a “death strip” in the middle – material that provided no cover or camouflage for anyone attempting to sneak across. Scaling the Berlin Wall configuration to a 2,000 mile border would require thousands of additional border guards, twice as much material as a single wall, and more than twice the land. Still wouldn’t stop persons wishing to illegally enter the United States from taking to waterways and entering through California and the Gulf coast states. To say nothing of people who come in through proper channels and simply overstay their visa.
But let’s assume that a significant portion of illegal immigration does come by land across the Mexican border at points that are not proper border crossings. For far less than the low-ball estimated cost of a wall being provided, we could have fifty thousand of autonomous drones (I’ve watched enough movies to advocate for unarmed drones) and solar charging stations. Existing border patrol agents would be notified when a target is acquired. Because we have SO many drones available, when a drone acquires a target it would signal for a new patrol drone to launch and then track the target until a border patrol agent detains the person.
If we’re that worried about people tunneling under to avoid detection, add drones with ground penetrating radar. If we’re worried about people coming in through Baja or Corpus Christi, extend the drone patrol line up the coast.
I don’t know if this proposed wall is meant to be a monument to American power (silly, but that’s kind of what the Great Wall is in China) or the sort of WPA project that Republicans actually like. But as an effective deterrent to illegal border crossings, it is an enormous waste of money, resources, time, and space.