President Trump's border wall is not real.

Well, I suppose it might become real — as in, it may physically come to exist — if this whole shutdown-for-funding gambit works. But it is not, will not, and cannot be real in the way Trump describes it. Whether constructed of concrete or steel slats or solid gold bricks mortared with the joyful tears of bald eagles, the wall will not work in the fantastical way Trump says it will. Whatever is or isn't constructed, it will never be the wall Trump is pitching, because what Trump is pitching is not a border barrier. It is a feeling.

The Wall — and let Trump's preferred capitalization indicate I speak of his proposal, not any tangible boundary — is a symbol. It is sentimentalism given form, a coping mechanism, and a "monument to an ideology." The Wall is a way to make Trump and his supporters feel good, safe, accomplished, and protected, but it is not a real policy proposal connected to realistic policy outcomes, as is evident on multiple counts.

1. Barriers already exist in most places on the southern border where construction is feasible and worthwhile. This is demonstrable, as there are photos. These walls and fences cover nearly all the U.S.-Mexico border in California, Arizona, and New Mexico, states in which the land immediately adjacent to the border line is typically owned by the federal government. It is only the Texas borderlands, belonging to hundreds of private property owners (as well as Native American tribes, whose land cannot be confiscated without standalone legislation from Congress), which remain significantly unfenced.

Some of that is about the ownership issue, to which we'll return below. But logistical concerns are as pressing as legal ones because dangerous, remote terrain would make development difficult, risky, and expensive — just as it already makes illegal border crossings.

2. Barriers can be gotten over, under, and around. Trump himself realizes this, occasionally. "You put that plank up, and you dig your footings, you put that plank up — there's no ladder going over that. If [would-be immigrants] ever get up there, they're in trouble, because there's no way to get down," he said in 2015 while outlining a plan for a 30- to 50-foot concrete wall which could prove unconquerable by household ladders from Home Depot. Then, as in an unwilling punchline, he added: "Maybe a rope."

Maybe a rope, indeed. Or maybe a ladder after all. Maybe even a rope ladder! Or maybe a tunnel, as the steel slat fence design Trump tweeted in December appears to show a barrier which does not extend into the ground. The thing about having a nearly 2,000-mile border, much of it running through uninhabited desert, is there's a whole lot of space to test ingenious new ways to overcome even the most beautiful of fences.

3. Illegal border crossings are not the main source of illegal immigration. While large caravans of Central American migrants may have grabbed more headlines, for more than a decade visa overstays have accounted for a larger portion of illegal immigration to the United States than illicit border crossings. A visa may be granted for work, education, or tourism, and when it expires, the person simply does not go home.

About four in 10 of the roughly 11 million undocumented immigrants in the United States are thought to be here because of visa overstays, and that proportion is increasing. Between 2004 and 2014, overstays rose from one third to two thirds of new additions to the undocumented immigrant population. By 2016, estimates from the Department of Homeland Security indicate overstays may outnumber successful illegal border crossings by as much as seven to one. That means even impenetrable border barriers would have no effect on 85 percent of new illegal immigration.

4. Border barriers will not stop drugs or terrorists. This is so for two different reasons. First, building more fences will not stop drugs because drugs are extremely profitable. As long as the United States continues its tragically ineffective war on drugs, drug cartels will figure out ways to overcome any obstacle to get their product into the country.

"The only law that cartels do not break is the law of supply and demand," explains Paul Kan at War on the Rocks. And "as new barriers along the border increase risks for the cartels," he continues, "they will innovate smuggling operations, raise their prices to keep profits flowing, and stimulate new domestic markets in Mexico and on the U.S. side of the border." They already did this "after 9/11, the last time the United States seriously tightened its border security," Kan adds. They can do it again.

The second reason is that unfenced borderland is not the exclusive thoroughfare for drugs or terrorists. For example, the Trump administration's own Drug Enforcement Agency has found the majority of heroin from Mexico enters the U.S. through legal ports of entry. Likewise, contrary the administration's disingenuous suggestion that 4,000 suspected terrorists have been caught at the southern border, the apprehension of "non-U.S. persons" on the terrorist watchlist averages about one per month, and more are apprehended at our northern border with Canada.

Could this situation change? Sure, but "eh, it's possible" is not a compelling argument for spending billions of dollars on fencing.

5. The logistics of building more border barriers are inimical to principles of liberty and limited government. This may not matter much to the American right in 2019, but give this old-timer a pass. To construct barriers on the unfenced portions of our southern border, especially in Texas, the federal government would have to confiscate private property on a mass scale. This has happened before, and it did not go smoothly.

Even with a "military version" of eminent domain — and Trump's plan to start construction by declaring a national emergency seems highly unlikely to pass legal muster — seizing hundreds of miles of border land from private and tribal owners would be a long, complex, expensive, and incredibly bitter process. (The Texas Tribune's excellent reporting on this subject is a must-read for those imagining there is any truth in Trump's promises of a quick and easy build.) And not to belabor the obvious, but it would also entail the federal government forcibly taking the private property of hundreds of Americans citizens for a feckless project they do not support.

The wall will not work in the fantastical way Trump says it will, and because of that it will not be the Wall. Dragged out of Trump's fevered thoughts and into reality, the Wall is not a policy. It is a sentimental source of comfort. It makes its enthusiasts feel good. That's understandable, but it's no basis for policy.