Is Building a Wall on the Mexican Border Good Policy or Simply Off-the-Wall?

Last week, Trump signed an executive order for one of his most controversial presidential campaign promises: build a wall on the Mexican border and make Mexico pay for it. While some Republicans have suggested using a border adjustment tax, the Trump administration suggested putting a 20 percent import tax (i.e., tariff) on all imported goods crossing the U.S.-Mexican border to have Mexico pay for the wall. If Trump knew how tariffs worked, he would know that it is the American consumers that would ultimately pay the tax to fund the wall.

What Trump is pushing for is hardly original. Border walls have been built throughout history, the two most famous being the Great Wall of China and the Berlin Wall. Border walls are used by a number of developed countries, and are typically built to either keep people in or keep them out. In this case, Trump would like to replace the 600-plus miles of fence that exist on the border (see below) and build a concrete wall, both to replace the current fence walls on the border and to extend the wall to new portions of the border. The idea is to show that Trump is attempting to address the issue of illegal migration into the United States, particularly with regards to crime. What I will do in the proceeding paragraphs is look at the potential costs, benefits, and obstacles to building a wall, as well as the arguments for building a wall on the U.S.-Mexican border, to see if the proposal can withstand scrutiny.

The Extent of the Problem of Undocumented Immigrants
Since the Great Recession, more undocumented immigrants have been leaving the United States than entering it, which negates Trump's claim of "immigrants pouring in." The number of undocumented immigrants apprehended should tell us how much illegal immigration has been declining. Because the Mexican economy has been improving, more Mexicans have been leaving the United States than entering it since 2009.

Let's take a look at some demographics about undocumented immigrants. About 40 percent of those considered unauthorized immigrants are individuals who entered the country legally, but overstayed their visas. No wall is going to stop those 40 percent from overstaying their visas. Let's also consider that only 52 percent of those unauthorized immigrants are Mexican, and that percentage is experiencing a decline. Much of the remaining 48 percent of unauthorized immigrants has to do with the refugee crisis in Central America.

On top of all of this, undocumented immigrants are not causing a fiscal drain, they are not more likely to commit crimes (also see here and here), and they actually pay taxes. Undocumented immigrants are clearly not the threat that Trump thinks they are, but contrary to fact, let's assume for a moment that they are. What else is there to consider when building the wall?

[3/21/2017 Addendum: The Cato Institute just came out with a policy brief that found out that illegal immigrants are 1.8 times less likely to commit a crime than a native-born citizen.]

Effectiveness of a Border Wall
Admittedly, a concrete wall could address some of the issues that come with a fence (e.g., difficult to maintain, easier to penetrate, easier to climb over or dig a tunnel under). One can also find some examples of where walls have arguably worked. However, there are a few considerations to determine whether a concrete wall would be all the more effective than the fences presently on the border:

• There is not adequate technology to detect tunnels, which is something the concrete wall would not solve. 
• The opaque nature of a cinder block wall would mean that border agents could not anticipate or mobilize to deal with those attempting to cross.
• A 2016 Migration Policy Institute (MPI) policy brief looked at border walls throughout the world concluded that they are "relatively ineffective."
• As a 2009 study from the Congressional Service Research shows (p. 26), building a fence has only rerouted immigrants to enter from less heavily guarded areas on the border. The MPI confirms this by saying that smugglers simply avoid the most heavily guarded areas and cross the ones that are not well-guarded. 
• There are also the migrants who will climb over with a rope, use underground tunnels, or be smuggled by coyotes. 

Cost of Building the Wall
In 2009, the Government Accountability Office (GAO) estimated that it would cost about $3-4 million per mile to construct a fence across the border. With a border of 1,981 miles, that would mean that a fence would cost about $5.9-7.9 billion, and that's with figures from 2009. Also keep in mind that those figures are for a fence, and not for a wall. As the Bernstein Group, the consulting firm that wrote up an analysis of Trump's wall idea back in July 2016, points out, $7 billion has been spent on building fences on the border since 9-11. More to the point, this analysis estimated that Trump's idea to build a 40-foot-tall, 7-foot-deep, 1,000 mile-long concrete wall on the border would cost a minimum of $15 billion, but could cost as much as $25 billion. MIT estimates that it could cost as much as $27-40 billion. These figures would fluctuate depending on the height of the wall, the materials used, and the length of the wall, but in any case, it would be more expensive than Trump's estimation of $8-12 billion.

Cost of Maintaining the Wall
Costs of the wall go beyond the initial construction because walls are incapable of apprehending would-be immigrants. Much more than a wall would be needed to secure the border. As Trump's Homeland Security Secretary, John Kelly, recently admitted, it will also take manpower, surveillance, and there are other security measures. Maintaining the wall would cost an estimated $750 million annually.  Security is tricky to maintain, as this 2016 report from the Congressional Research Service illustrates. Because Trump wants to cover more of the border than is already covered, security will get more complicated and expensive. Since Trump has not made any statement regarding how he is to secure the wall, those costs remain unknown until such a time he reveals his security plan. However, it is safe to assume that it would add to the $13.9 billion already allotted for the U.S. Customs and Border Protection for FY 2017.

Legal Considerations
First, just because President Trump signed an executive order for a border does not mean that he can start building the wall. He first needs to have the funds appropriated by Congress. Then there is the issue of private land. According to the GAO, about a third of the land on the border (mostly in Texas) is private land (GAO, 2015, p. 5). To erect the border in certain places in Texas, there needed to be many lawsuits between Texan citizens and the federal government, and even then, there were considerable delays (DHS, 2009) and threats from the Bush administration. Given that Trump wants to develop the wall on Texan land, he will need to deal with hundreds of landowners. And let's not forget there are tribal lands on the border, which complicates things because federal law recognizes Indian tribes as separate political entities.

Unintended Consequences

• It's quite possible that militarization on the border has actually made undocumented migration more prevalent over the years (Massey et al., 2016). 
• Mexico is the United States' third largest trading partner. Considering that undocumented immigrants don't possess the threat that Trump perceives, it wouldn't be wise to exacerbate tensions with one's neighbor.
• While Trump is making it seem like Mexico will pay for the bill, both proposals of the border adjustment tax and an import tax (a.k.a., a tariff) would mean the American people are footing the bill. 
• As previously mentioned, a border of this length and geographical terrain means that undocumented immigrants will simply re-route their entry into the country. 
• The wall also has environmental impacts, most notably of adversely altering migration patterns of most animals (except birds).

Postscript: Building a concrete wall on the U.S.-Mexican border is mere feel-good, populist immigration policy that makes certain voters happy because he is fulfilling a major campaign promise. Much like his $141.3 billion plan to deport immigrants, Trump's plan to build a wall makes little sense, fiscally or otherwise. Aside from not making sense, it does not have the popularity that some might think it does. A recent ABC found that only 37 percent of Americans favor building the wall, while Pew Research found that figure to be 39 percent of Americans. Even better, 72 percent of those living in border cities oppose the wall.

If this administration ends up putting resources into focusing on undocumented workers, building a more extensive concrete wall is hardly the best use of resources. What would be even better than focusing on undocumented workers is having our politicians focus on how to improve legal immigration so that the United States can reap the economic benefits of immigration. I could find better ways to spend billions of taxpayer dollars than building an ineffective, expensive, pointless wall, which is why I hope that Congress doesn't end up providing Trump with the funding required to build this waste of money.

For more information, read this wonderful policy brief by the Cato Institute covering this topic.