Paraphrasing poet Robert Frost ("good fences") is only symbolic since the words are interchangeable. They can also be used as "lines," "barriers," or any other obstacle to traffic, whether man or beast. The title is also erroneous; fences "make" nothing but serve only to separate otherwise "bad" neighbors.
Historically, human walls serve only two purposes, to either keep people in or out. The Berlin Wall during the Cold War served the first purpose; President Trump's project is meant for the second. Either way, walls are usually a last resort, short-term, awkward, ugly, and violent. Almost nobody likes them but sometimes they are necessary, at least in the minds of the builders.
Borders are "boundaries" that can be both human and geographic. Human boundaries are psychological and define codes of behavior that should be observed. The Ten Commandments are God's "borders" for mankind. Similarly, nations, empires, cities, counties, jurisdictions have their own boundaries which are also meant to be observed. When they are not, barriers are erected to enforce the boundary line.
These are universal human realities, not invented by Trump or any other official. Borders have been essential for existence since the beginning of time, and no technology or global movement has yet dented this reality. Thus, no one should be surprised that in a nuclear-space age, the U.S. still clings to a border-wall as the top security issue. That includes both those opposed to it and those in favor.
Borders have defined history as much as warfare itself. U.S. borders were expanded by both purchase and conquest. The Louisiana Purchase (1803) bought land from France that expanded the American border from the Mississippi to the Rockies. The defeat of Mexico (1848) converted over half of Mexican territory into U.S. land to the Pacific Ocean.
The "nation-state" system began with the Peace of Westphalia (1648) and defined territoriality as definitive for existence. Today, there are 193 such entities in the United Nations, and each guards its frontiers with equal vigilance. Sometimes this hasn't worked.
In 1794, Poland ceased to exist, absorbed by its neighbors, Russia, Prussia, and Austria. Poland "resurrected" in 1919 (after World War I) only to disappear again in 1939 by the same culprits (without Austria). Then it was occupied by the USSR only to reappear again as a sovereign in 1991 (with the end of the Cold War). To the Poles, borders are critical for life.
Other examples abound. Using the same general region, Austria lost its entire empire in 1919 and became a tiny ski resort. In 1938, it lost even that ("Anschluss") to Hitler, only to re-emerge as a ski resort again in 1945.
Most countries are small and, thus, guard their borders jealously. The United States, being extremely large, has not usually had this problem. The northern border needs no mention as a security issue. Historically, the southern border was always just a nuisance; nobody feared a Mexican invasion. Today, the issue has grown to enormous heights and has defined American security since at least 2016. How ironic: an abstract, an idea, occupies chief national attention. This idea even shut down part of the government itself.
Throughout history, walls have defended existence ("existential") when territory was threatened. Thus, the U.S. today, after all, is no different. In his definitive book, Walls: A History of Civilization in Blood and Brick (2018), archaeologist David Frye notes that: "No invention in human history played a greater role in creating and shaping civilization than walls. Without walls, there could never have been ... Chinese scholars, Babylonian mathematicians, or Greek philosophers. Moreover, the impact of walls wasn't limited to the early phases for most of history, climaxing spectacularly during a 1,000 year period when three large empires - Rome, China, and Sassanid Persia - erected barriers that made the geopolitical divisions of the Old World all but permanent."
Most people are familiar with history's more famous walls, the "Great Wall" of China, Hadrian's (Britain), Jericho (Jerusalem), Trojan (Turkey), Ston (Croatia), Babylon (Iraq), Zimbabwe, Sacsayhuaman (Peru), Diyarbakir (Turkey), West Bank (Israel), "Iron Curtain" (Berlin).
But, as author Frye has emphasized, the net effect of walls in history was to preserve civilization against outside "barbarians." These included an assembly of structures around an astonishing number of countries: Syria, Egypt, Greece, Iraq, Bulgaria, Ukraine, Romania, Turkey, Russia, Britain, Peru, Afghanistan, Iran, Azerbaijan, Uzbekistan, Libya, China, Korea ("partial" list).
Now, in 2019, approximately 77 countries have some form of wall or structure to protect their frontiers, with a reported 45 planning same. In Europe itself, home of the EU, 800 miles of fencing has been built since 2015, including in Bulgaria, Hungary, Slovenia, Macedonia, Austria, and France.
Now the U.S. is contemplating one, but only the administration in power. Many Americans, especially Democrats, oppose "Trump's Wall," and have refused his budget. Much of this, of course, is pure American politics and will probably be compromised sooner or later.
In the long-term, a far better solution would be a mutual arrangement between the two governments, diplomacy being the "art of the possible." Barring that, a barrier, by any name, will certainly go up.
In summarizing internal debates that occupied the construction of walls before and now, author David Frye has noted: "For every person who sees a wall as an act of oppression, there is always another urging the construction of newer, higher, and longer barriers. The two sides hardly speak to each other."