The Chinese built many walls over many centuries to keep out one or another group. They had varying success but also had to repeatedly rebuild some sections that eroded away and was breached from time to time by various groups. The Great Wall of China was largely completed in the Ming dynasty. Clearly, the Ming dynasty is no longer in charge of China so ultimately, it had no useful effect. Now it is largely a tourist attraction. The proposed wall at our border will not be grand enough to ever warrant a tourist's glance - eyesore would be more reasonable.
The Romans built a nice pair of walls in northern England - Hadrian's Wall and later the Antonine Wall in Scotland. For as long as the Romans cared to garrison the walls, they were largely effective. But it is clear that the reason they were effective were the garrison forces manning them. The walls themselves were formidable, but without legions standing guard every few Roman miles, they wouldn't have stopped anyone that seriously wanted in. I included this pair because they went across the whole of England and Scotland, having a direct correlation to our proposed border wall. Eventually, the cost of the legions and foreign battles got to much for the people of Rome to stomach and the empire shrank. Leaving England was an easy choice to make.
Another famous fortification - the Maginot line in France, ended up being useless because the Germans just went around it in World War II. This is the primary problem with any fixed fortification today. If it is worth getting something from A to B, someone will find a way to do it. Drugs are profitable, so moving them from producer to consumer will always find a way - legal or not to get done. The harder the movement is made, the more profitable the items will be when they reach B and the more money can be expended in transiting from A to B while still making a profit. A wall can be climbed over or tunnelled under or just cut through. It happens all the time now. If you want to detect all of these things occurring along the line, you need some fairly sophisticated monitoring equipment all along the US side of the wall. If you have that, why not skip the wall and just pay for some rapid deployment forces like the Roman garrisons?
Of course in between the Romans and the French, technology advanced. People developed hot air balloons and then - gasp - helicopters, planes, and drones, that could just fly over walls, rendering them pretty much useless unless you had military with orders to shoot you down. We probably wouldn't do that immediately - just force you to land some place - so flying over and landing is a real option if the price is right. If the border is not an option just charter a plane and land in an less used airstrip, rent a submarine, use boats and the vast coastline, or find a different means.
The Germans spent quite a bit of money fortifying France, but in the end, a less fortified spot was found and the Allied forces pushed through. We also attacked up through Italy and the Russians were on the offensive in the East. No walls help when they only protect one border. If the Mexican border becomes too tough, switch to Canada.
A final example to be considered is the Berlin wall (or really the entire Iron Curtain). Again, this was successful because it was designed largely to keep people in and the rulers had no issues at all shooting or blowing people up with anti-personnel mines who tried to cross. Mined zones made the wall a bit less porous than a normal wall, but it was the armed forces that made the difference. Well, that and the very real possibility that all of a defector's friends and family might get shipped off to a gulag. The wall by itself wouldn't have kept anyone in in many places along the border.
There's the other issue that a good stretch of the Mexican border is desert that you don't really want to cross in the first place and a fixed border wall that is impassible would be awful for the environment, but those are just other minor reasons why a solid wall along the whole border would be unnecessary and just plain bad.
I've discussed immigration in other posts, so I won't repeat everything I've said here. But there are some basics we need to come to terms with. Family size is shrinking. People are delaying getting married and starting families. We aren't to the point of Japan yet which has serious problems with ageing populations, but we are well on the way. We need to start having bigger families or we need to support legal immigration and make the process easier. Do we want terrorists? Of course not. But only a very tiny fraction of those trying to immigrate are terrorists. Do we want criminals? Of course not. But a higher percentage of US citizens commit crimes than immigrants. They're thankful just to be here. Do we want drug crimes? Of course not. But the only answer to that is decriminalization of many drugs. Take the profit out of it and the criminal side dries up.
This is a nation of immigrants. The only difference is how far you go back before the immigration occurred. Very few inhabitants trace their immigration back to before the Bering Strait was formed, but we're all immigrants at some point. Stop splitting up families. If people are here and are productive, allow them to become citizens and start getting taxed like everyone else. Be compassionate to those fleeing tyranny or war. Invite them in. Show them Christian love. Make a difference in the world for good for a change.
The countries of Europe formed a union. They opened their borders to trade and to work. Those countries are much smaller than the US. We have several states larger than many of the countries in the union. But they survive without ugly border fences all along each of their borders. We should be considering a free trade area between Canada, the United States, and Mexico if considering anything. Perhaps include everything down through Panama. That would have some of the same issues the EU is now facing between wealthy and poorer members, but perhaps we could look to their problems and form something better that would avoid the issues they are seeing. The French are still French. The Germans are still Germans. But they've also aligned with others to try to be something more powerful economically. We should consider that as well.
And get the man a map and some LEGO bricks already. People are suffering with the shutdown. If you thought the government was inefficient before, just think how inefficient it is those who are laid off get their checks for not doing any work at all - as usually happens. Find a way to pay those who are having to work now without pay. I realize that those who have been laid off were not at fault. Neither was my father when the place he worked at changed hands several times. He didn't get make up pay for the time he was off and one of my childhood memories was being asked to save water to reduce the bills at times between the business being open. Maybe if there wasn't a mostly guaranteed pay check for those who were laid off or those who are having to work without pay, the adults in the government would prevail more often and we wouldn't have these shut downs.
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