A Sense of Wander: Something there is that doesn't love

Something there is that doesn't love a wall ...

Robert Frost (1874-1963), "Mending Wall," in North of Boston, Henry Holt and Company, 1917. Online: http://www.bartleby.com/people/Frost-Ro.html .

Introduction

On June 16, 2015 Mr. Donald John Trump announced that, if elected President of the United States:

“I would build a great wall. And nobody builds walls better than me, believe me. And I’ll build them very inexpensively. I will build a great great wall on our southern border and I’ll have Mexico pay for that wall.”
[Source: http://www.politico.com/story/2015/06/donald-trump-2016-announcement-10-best-lines-119066; see also http://blogs.wsj.com/washwire/2015/06/16/donald-trump-transcript-our-country-needs-a-truly-great-leader/]

Length

Leaving aside the advisability of such a project -- is it possible? Could you really build a wall along the entire 1,989 miles (3,201 kilometers) of the US-Mexico border?

Keep in mind there already is a "wall" between the US and Mexico. Sort of. At the moment there are 652.6 miles (1,050.25 kilometers) of fencing; of that, 299.8 miles (482.5 kilometers) are vehicle barriers (and not intended to stop pedestrians). To put it another way, we already have a "wall" along more than one third of the border.

And 652.6 miles is a lot of wall, right?

Actually, no. By historical standards it's not all that impressive. The fact is, people have been constructing "Great Walls" (and barriers and fences) for an awfully long time.

According to Evan Andrews, the earliest "great wall" was built approximately 4,000 years ago, by the Sumerians; it's called "the Amorite Wall" because it was made to deter the Amorites.¹ The ten longest great walls (including fencing and discontinuous barriers) that have ever existed are:

21,196 km: The Great Wall of China
5,614 km: Dingo Fence ("Dog Fence")²
4,000 km: Inland Customs Line ("Great Hedge of India," "Indian Salt Hedge")
3,406 km: India-Bangladesh Barrier
3,256 km: Rabbit-proof Fence ("State Barrier Fence of Western Australia")²
2,700 km: Moroccan Wall ("The Berm") [located in Western Sahara]
2,688 km: The Atlantic Wall [World War II, coastal Europe and Scandinavia]
1,420 km: China-North Korea Barrier
1,393 km: Inner German Border [between East and West Germany]
1,000 km: Serpent's Wall [Ukraine]

Construction

Walls (barriers, fences, whatever) can be made from almost anything -- sand, clay, packed earth, caliche;³ wood, bamboo; cacti, Euphorbias, thornbushes, ocotillo;⁴ mud brick, bricks and mortar, dry stone, concrete; iron, steel; even glass. The point of a Great Wall is stopping people. Today there's a strong preference for chain-link and barbed wire fencing (both invented in the 19th century).

     To each the boulders that have fallen to each.
     And some are loaves and some so nearly balls
     We have to use a spell to make them balance:
     "Stay where you are until our backs are turned!"
     Robert Frost, "Mending Wall"

Stone, as Mr. Frost noted, does not always make the best walls.

What does Mr. Trump propose to build his wall out of?

On August 19, 2015:

"So you take precast [concrete] plank. It comes 30 feet long, 40 feet long, 50 feet long. You see the highways where they can span 50, 60 feet, even longer than that, right? And do you a beautiful nice precast plank with beautiful everything. Just perfect. I want it to be so beautiful because maybe someday they'll call it The Trump Wall. Maybe. So I have to make sure it's beautiful, right? I'll be very proud of that wall. If they call at this The Trump Wall, it has to be beautiful. And you put that plank up and you dig your footings. And you put that plank up -- there's no ladder going over that. If they ever go up there, they're in trouble, because here's no way to get down. Maybe a rope."
[http://www.realclearpolitics.com/video/2015/08/19/trump_on_border_maybe_theyll_call_it_the_trump_wall.html]

On December 2, 2015:

"I'll tell you what it's going to be made out of. It's going to be made of hardened concrete and it's going to be made out of rebar and steel."
[http://www.c-span.org/video/?c4589206/donald-trump-explains-plan-border-wall]

On February 9, 2016:

"... we don’t need 2,000 [miles of wall], we need 1,000 [miles of wall] because we have natural barriers, et cetera, et cetera, and I’m taking it price per square foot and a price per square, you know, per mile, and it’s a very simple calculation. I’m talking about precasts [concrete panels] going up probably 35 to 40 feet up in the air."
[https://www.washingtonpost.com/news/fact-checker/wp/2016/02/11/trumps-dubious-claim-that-his-border-wall-would-cost-8-billion/]

On February 12, 2016:

"So I got a call from one of the reporters yesterday, and they said, 'The president of Mexico said they will not under any circumstances pay for the wall," Trump said. "They said to me, 'What is your comment?' I said the wall just got ten feet higher."
[http://www.msnbc.com/msnbc/donald-trump-says-his-wall-would-cost-8-billion]

On February 25, 2016:

WOLF BLITZER: So if you don't get an actual check from the Mexican government for $8 billion or $10 billion or $12 billion, whatever it will cost, how are you going to make them pay for the wall?
TRUMP: I will, and the wall just got 10 feet taller, believe me.
[https://www.washingtonpost.com/news/the-fix/wp/2016/02/25/the-cnntelemundo-republican-debate-transcript-annotated/]

On March 2, 2016:

"We need 1,000 miles and we have all of the materials. We can do that so beautifully. And this is going to be a serious wall. This is going to be high wall. This is going to be a very serious wall."
[http://time.com/4245134/super-tuesday-donald-trump-victory-speech-transcript-full-text/]

On June 16, 2016:

"I would build a great wall, and nobody builds walls better than me, believe me, and I’ll build them very inexpensively, I will build a great, great wall on our southern border. And I will have Mexico pay for that wall."
[http://blogs.wsj.com/washwire/2015/06/16/donald-trump-transcript-our-country-needs-a-truly-great-leader/]

It seems that the proposed wall is supposed to be made out of concrete (probably precast concrete panels). It's going to be "high" (somewhere between 35 and 60 feet [10 to 18 meters]) tall. It's going to be "beautiful." And it's going to be "great."

So let's consider concrete. Concrete is a complex physical and chemical mix of aggregate (sand, gravel, broken stone) and cement, which is made from lime (calcium hydroxide, also known as "slaked lime"), combined with water, which slowly hardens. Making concrete is energy intensive. It's also quite polluting; something like 5% of global human-created carbon dioxide comes from manufacturing cement.⁵

The earliest known deliberately created concrete (as opposed to natural concretes, like caliche) dates back about 2,700 years. The Nabatean Arabs in Petra, in what is now Jordan, used it to create waterproof cisterns. The Romans, of course, became masters of concrete. Many examples of Roman concrete are still visible today. The roof of the Pantheon, created in 142 CE, is still one of the world's outstanding structures.⁶

Concrete can be durable, but it's not permanent. Leaving aside errors and omissions (incorrect aggregates, contaminated water) and environmental damage (freeze-thaw, air pollution, salt, acids), one of the biggest problems with modern concrete is steel.

Most concrete today is reinforced. Generally speaking, that's a good thing. It makes it possible for concrete to span enormous distances and support great weight. But most reinforced concrete is made with steel. And steel rusts. The result is a chemical reaction that eats concrete from the inside out; it's sometimes called "concrete cancer."⁷

"Early 20th-century engineers thought reinforced concrete structures would last a very long time – perhaps 1,000 years. In reality, their life span is more like 50-100 years, and sometimes less. Building codes and policies generally require buildings to survive for several decades, but deterioration can begin in as little as 10 years."
[https://theconversation.com/the-problem-with-reinforced-concrete-56078]

Can you make a "great wall" with concrete? Yes, for a given value of "great":

The Inner Harbor Navigation Canal-Lake Borgne Surge Barrier near New Orleans is 1.4 miles (2.25 kilometers) long and made of concrete panels 26 feet tall.
The wall surrounding the Bab Amr quarter in Homs, Syria is 3 miles (5 kilometers) long and constructed of concrete panels 3 meters tall.
The walls around Alphaville in Sao Paulo, Brazil are 40 miles (64 kilometers) long and (mostly) made from 2.5 meter tall concrete topped with barbed wire (it's not quite clear if this is poured or pre-cast concrete).
Israel's West Bank Barrier (also known as "The Separation Fence," "The Separation Barrier," "The Security Fence," "The Anti-Terrorist Fence," "The Annexation Wall," "The Apartheid Wall," and "The Apartheid Fence") is mostly constructed of barbed wire and chain-link fence, but about 5% is built from concrete panels which are up to 8 meters tall; since the entire barrier is supposed to be 650 kilometers (403 miles) long when completed, that would mean that the concrete portion is roughly 30 kilometers (19 miles).
South Korea's Saemangeum Seawall is mostly concrete, and is 33 kilometers long and the average height is 36 meters (118 feet) (note that this is poured concrete, not pre-cast concrete panels).
China has proposed a system of concrete seawalls along its coastline that will, if completed, extend approximately 11,000 kilometers (6,835 miles) (note that this is poured concrete, not pre-cast concrete panels).⁸

Purpose

Before I built a wall I’d ask to know

What I was walling in or walling out,

And to whom I was like to give offense.
Robert Frost, "Mending Wall"

Mr. Frost brings up a valid point: Why build a wall?

What Mr. Trump has proposed is a border wall; that is, a separation barrier along an international border. Its purpose is to stop the movement of people, to prevent people from entering (or leaving) a country.

Border barriers are actually fairly common today. According to Rick Noack there are literally dozens of walls (of one sort or another) separating countries today.⁹

In alphabetical order:

Belize-Guatemala barrier (proposed)
Botswana-Zimbabwe barrier
Brunei-Limbang border (Brunei-Malaysia)
Bulgaria-Turkey border
Ceuta border fence (Spain-Morocco)
China-North Korea barrier
Chinese-Korean border fence
Costa Rica-Nicaragua border
Egypt-Gaza Strip barrier
Estonia-Russia border fence
Hungary-Croatia barrier
Hungary-Serbia barrier
India-Bangladesh barrier
Indian Kashmir barrier
Indo-Bangladeshi barrier
Indo-Burma barrier
Iran-Pakistan barrier
Kazakh-Uzbekistan barrier
Korean Demilitarized Zone
Kuwait-Iraq barrier
Macedonia-Greece border
Malaysia-Thailand barrier
Melilla border fence (Spain-Morocco)
Pakistan-Afghanistan barrier
Pakistan-Iran barrier
Saudi Arabia-Iraq barrier
Saudi Arabia-Yemen barrier
Slovenia-Croatia barrier
South Africa-Zimbabwe border
Turkmenistan-Uzbekistan barrier
Ukraine-Russia barrier
United Arab Emirates-Oman barrier
United States-Mexico border fence (partially completed)
Uzbekistan-Afghanistan barrier
Uzbekistan-Kyrgyzstan barrier

In order by length:

3,360 km: United States-Mexico barrier (proposed; 1,050.25 km completed)
3,268 km: Indo-Bangladeshi barrier
2,900 km: South Africa-Zimbabwe Border
2,400 km: Pakistan-Afghanistan barrier
2,000 km: Ukraine-Russia barrier
1,700 km: Turkmenistan-Uzbekistan barrier
1,624 km: Indo-Burma barrier
1,416 km: Chinese-Korean border fence
900 km: Saudi Arabia-Iraq barrier
870 km: Uzbekistan-Kyrgyzstan barrier
700 km: Iran-Pakistan barrier
650 km: Malaysia-Thailand border
644 km: Slovenia-Croatia barrier (under construction)
550 km: Indian Kashmir barrier
500 km: Botswana-Zimbabwe barrier
410 km: United Arab Emirates-Oman barrier
248 km: Korean Demilitarized Zone
209 km: Uzbekistan-Afghanistan barrier
193 km: Kuwait-Iraq barrier
175 km: Hungary-Serbia barrier
108 km: Estonia-Russia border fence
75 km: Saudi Arabia-Yemen barrier
45 km: Kazakhstan-Uzbekistan barrier
41 km: Hungary-Croatia barrier
30 km: Bulgaria-Turkey border
30 km: Macedonia-Greece border
20 km: Brunei-Limbang (Brunei-Malaysia)
11 km: Melilla border fence (Spain-Morocco)
8 km: Ceuta border fence (Spain-Morocco)
3.1 km: Egypt-Gaza Strip barrier
-- Belize-Guatemala (proposed)
-- Costa Rica-Nicaragua (proposed)

Cost

"The wall is probably [going to cost] $8 billion, which is a tiny fraction of the money that we lose with Mexico"
[http://www.cnn.com/2016/02/09/politics/donald-trump-border-wall-cost-8-billion/]

The 652.6 miles (1,050.25 kilometers) of the current US-Mexico border fence has already cost somewhere between $2.4 billion and more than $7 billion. So far.¹⁰

Construction costs vary depending on local terrain. According to Elisabet Vallet, in 2008 the estimate was $1 million to 4.5 million per kilometer, but in the Otay Mountains near San Diego the cost was $6.4 million per kilometer. Samantha Sais reported slightly different figures in 2013: between $400,000 to $15 million per mile, averaging $3.9 million per mile; to deal with the more challenging topography near San Diego (presumably the Otay Mountains) $58 million was spent to build a 3.5 mile section of fencing.¹¹

The highest elevation in the Otay Mountains is 3,566 feet (1,087 meters), and along the actual border the highest elevation is about 1,200 feet (366 meters). There are places along the US-Mexico border, near Sierra Rica in Chihuahua, and near the town of Sunland Park New Mexico, for example, where the border crosses mountains that are nearly 5,000 feet tall (1,500 meters). If it cost roughly $15 million per mile in the relatively low elevations located near San Diego, it would presumably cost at least as much (if not more) in these locations.

Is a figure of $8 billion to build a two thousand mile (or maybe just a one thousand mile) concrete wall reasonable?

Probably not. Mr. Trump has changed the estimated cost of his wall several times, most recently to as much as $12 billion. Experts believe that figure is extremely low; most place the cost at $25 billion. And walls have to be maintained. In 2010 US Customs and Border Protection spent $7.2 million just repairing 4,037 holes in the current fence.¹² Maintenance costs for the 652.6 miles of the current barrier have been estimated at $49 billion over 25 years, or roughly $2 billion per year.¹³ It's reasonable to assume that maintenance costs on a longer fence would be considerably higher.

It has been suggested that a "virtual fence," a high tech system of sensors, cameras and drones, might be a less expensive alternative. That hasn't proven to be the case.

A 53 mile (85.3 kilometers) pilot project in Arizona, "Project 28" of the "Secure Border Initiative network" (or "SBInet") that began in 2006 was cancelled in 2011 after becoming a billion dollar failure (with projected costs ballooning up to $30 billion). Boeing, the contractor, failed "to understand the complexities of border management [which] can ultimately push costs up for government clients while undermining the value of the technologies implemented." The program suffered from management and technology failures. because "Boeing has had trouble getting the different components to work together."¹⁴

Static barriers by themselves are not particularly effective at stopping migration. Whatever kind of wall is built, people are going to be needed to patrol and maintain it. In a highly critical article ("dyspeptic" might be a better word) Mark Hewitt summed it up this way: "If the cops go home, the illegals will defeat the fence."¹⁵

People have to be paid. There are currently over 21,000 Border Patrol Agents; salaries start at $49,000 per year,¹⁶ which means that salaries alone cost over $1 billion per year -- and that's with our current wall. It seems reasonable to assume that more Agents will be needed if the wall is expanded, vastly increasing personnel expenses.

And there are other costs: private lands along the border would have to be purchased; Native American lands would have to be acquired (which would involve treaty negotiations); there have been vehement objections from Mexico, potentially causing a political crisis, as well threatening our relationship with our second largest trading partner (Mexico already objects to the current fence, and is positively apoplectic at the idea that they would pay for a new one);¹⁷ and there are considerable environmental costs as well.¹⁸

And then there are the "costs" of unintended consequences. It's generally believed that the current US-Mexico border fence has prevented some people from entering the US. But many have simply shifted from relatively safe zones to desert and mountain areas that aren't currently "walled," resulting in hundreds of deaths.¹⁹ Of course, many people (half or more) who are in the US illegally don't cross the US-Mexico border at all. They enter legally (on student, tourist, or work visas) and simply "overstay."²⁰ A fence -- no matter how spectacularly long or how high or how "beautiful" -- would do nothing to deal with them.

Need and Desire

"I want it to be so beautiful because maybe someday they'll call it The Trump Wall. Maybe. So I have to make sure it's beautiful, right? I'll be very proud of that wall. If they call at this The Trump Wall, it has to be beautiful."
[http://www.realclearpolitics.com/video/2015/08/19/trump_on_border_maybe_theyll_call_it_the_trump_wall.html]

Who wants a wall?

A March 31, 2016 poll by the Pew Research Center found that only 38% of respondents nationwide were in favor of building a wall along the US-Mexican border. On the other hand, a June 28, 2016 poll by the University of Texas/Texas Politics Project found a slim majority (52%-48%) of Texans favored building a wall.²¹

Many public officials in the immediate border region are opposed to a wall:

"I think when you build a wall, it's a wall of shame."
Laredo, Texas Mayor Raul Salinas
[http://www.npr.org/templates/story/story.php?storyId=15315131]

"Why try to force [on] us your way of thinking when you don't even live here," he said. "It's not affecting you. And, if you're so worried about whatever you're worried about, why not build a fence around your state."
Brownsville, Texas Mayor Patricio Ahumada
[http://www.npr.org/templates/story/story.php?storyId=15315131]

"I say that those who want this fence don’t understand the border, don’t understand our sense of community"
Del Rio, Texas Mayor Efrain V. Valdez
[http://www.washingtontimes.com/news/2008/feb/21/texas-cities-oppose-border-fence/]

"I strongly believe we don't need it," he said. "It's an eyesore. It's a dangerous thing. We need to build relations with Sonora and Mexico."
Nogales, Arizona Mayor Arturo Garino
[http://www.cnn.com/2013/07/12/us/nogales-razor-wire/]

“There’s no boogeyman on the south side of the border. We know that.”
Former San Diego Mayor Jerry Sanders
[https://www.washingtonpost.com/national/build-a-wall-on-the-border-no-thanks-says-san-diego/2015/10/31/f821073e-71d9-11e5-8d93-0af317ed58c9_story.html]

"Like many communities on the border, we have a much more fluid idea about crossing it."
Jon Barela, New Mexico Secretary for Economic Development
[http://america.aljazeera.com/articles/2014/5/28/a-binational-townontheusmexicoborder.html]

There are many possible adverse results from building a border wall, but perhaps the most interesting is that it may actually increase illegal immigration:

"... the [current US-Mexico] barriers were effective enough to redirect the flow of migrants to more dangerous zones ... but ... the hardship of the border trip encouraged migrants to remain in United States territory for longer periods of time ... Hispanic migrants lost any incentive to remain near the American side of the border after crossing, as they were no longer able to shuttle between the two countries. ...The Hispanic population skyrocketed in areas of the United States that were previously "immigration free," and this amplified in a vicious cycle the identity conflicts that put pressure on the political system to reinforce the border deployment."²²

Final Thoughts

Is it actually possible to build a "beautiful" 2,000 mile wall (or maybe just a 1,000 mile wall), made of concrete, along the US-Mexico border?

Yes. Of course it is.

With enough money, given current technology, it could be done. It would cost roughly the same as the 2016 budget of the US National Institutes of Health, or the Federal student financial aid program, or the budget for NASA and all other Federally-funded science and research labs. It would cost roughly twice the budget of all Federally-funded programs for Special Education, and considerably more than the current budget for Customs and Border Protection.²³ It would damage relations with Mexico, and possibly with other nations, too. It would require a substantial increase in Border Patrol personnel. It would cause potentially terrible environmental problems.

But it could be done. If there was a reason to build it.

Migration into the US from Mexico is currently at its lowest level since the 1940s. According to the Pew Research Center, the current net migration rate from Mexico is actually less than 0%.²⁴ It was not our current border fence that was the crucial factor in this massive change (although increased enforcement of immigration laws certainly may have contributed to it). It was primarily because of changing economic and social factors, including the 2008 US economic recession. But the number one reason Mexican citizens give for returning to Mexico: Family reunification.²⁵

States have been building "Great Walls" to secure their borders for at least 4,000 years. Sometimes they've been effective. For a while. But they're never a permanent solution. People migrate for a variety of reasons -- economic, social, and environmental. The need (and the desire) to move doesn't end because there's a wall in the way. No wall is impregnable. Over, around or through, with enough effort, any wall can be overcome.

From Sumeria's Amorite Wall, to China's Great Wall, to the Berlin Wall, to the 3.1 kilometers of the Egypt-Gaza Strip barrier, "Great Walls" can impede the movement of people. But only at great cost, and only for a limited period of time. I can't help but wonder what our urge to separate ourselves (and to wall ourselves in) says about us, and what the final price of such an effort might be.

I see him there

Bringing a stone grasped firmly by the top

In each hand, like an old-stone savage armed.

He moves in darkness as it seems to me
Robert Frost, "Mending Wall"

Notes

¹ http://www.history.com/news/history-lists/7-famous-border-walls. It was 270 kilometers long and stretched between the Tigris and Euphrates rivers. Maybe it worked. There haven't been any Amorites since 1200 BCE.

² Australia is the home of two of the longest structures on the planet. They are both "pest exclusion fences" -- that is, they're designed to restrict the movement of animals, not people.

The "Dingo Fence" was finished in 1885, and is actually the result of joining together three smaller fences: Queensland's 2,500 kilometer (1,553 miles)"Great Barrier Fence" (or "Wild Dog Barrier Fence 11"), New South Wales's 257 kilometer (160 miles) "South Australian Border Fence," and the 2,225 kilometer (1,383 miles) "Dog Fence" in South Australia.

There are actually two "Rabbit-proof fences" in Australia; in addition to the 3,256 kilometers (2,023 miles) of the State Barrier Fence of Western Australia, there is the Queensland Rabbit Proof Fence (also known as the "Darling Downs-Morton Rabbit Board fence"), which is 555 kilometers (345 miles) long. See: http://www.amusingplanet.com/2013/11/dingo-fence-australias-5600km-dog-fence.html ; http://www.fencefence.com/stories/dingo-fence.html ; https://www.daf.qld.gov.au/plants/weeds-pest-animals-ants/pest-animals/barrier-fences/history-of-the-darling-downs-moreton-rabbit-board-fence ; http://www.rpfcp.com.au/rabbit-proof-fence-history-about/

³ Caliche is a naturally occurring cement, which forms when lime (calcium carbonate) binds various materials (sand, gravel, etc.). Caliche (also known as hardpan and calcrete) typically forms in arid climates (see: http://www.gly.uga.edu/railsback/VFT/VFTEC.html).

⁴ Fouquieria splendens (see: https://www.desertmuseum.org/kids/oz/long-fact-sheets/Ocotillo.php).

⁵https://web.archive.org/web/20070714085318/http://www.wbcsd.org/DocRoot/1IBetslPgkEie83rTa0J/cement-action-plan.pdf ; http://www.nrmca.org/sustainability/CONCRETE%20CO2%20FACT%20SHEET%20FEB%202012.pdf ; http://www.nytimes.com/2007/10/26/business/worldbusiness/26cement.html?_r=0

⁶ https://www.nachi.org/history-of-concrete.htm#ixzz31V47Zuuj ; http://www.concretenetwork.com/concrete-history/

⁷ https://theconversation.com/the-problem-with-reinforced-concrete-56078 ; see also http://www.cement.org/docs/default-source/th-paving-pdfs/concrete/types-and-causes-of-concrete-deterioration-is536.pdf?sfvrsn=4 ; http://www.rawstory.com/2016/06/the-problem-with-reinforced-concrete/

⁸ https://electronicintifada.net/content/it-fence-it-wall-no-its-separation-barrier/4715 ; http://america.aljazeera.com/articles/2014/3/12/visual-activism-activestillsphotographsthebarrierwall.html ; http://www.haaretz.com/israel-news/.premium-1.707775 ; http://www.eenews.net/stories/1059999621 ;
http://www.theguardian.com/world/ng-interactive/2013/nov/walls#homs ; http://phys.org/news/2010-04-skorea-world-longest-seawall.html ; http://csis.msu.edu/sites/csis.msu.edu/files/Science-2014-Ma-912-4.pdf

⁹ https://www.washingtonpost.com/news/worldviews/wp/2014/11/11/these-14-walls-continue-to-separate-the-world/ ; see also http://blog.mondediplo.net/2013-11-29-Et-la-frontiere-devint-un-marche-prospere-et ; https://www.washingtonpost.com/politics/trump-on-the-us-mexico-border-building-a-wall-is-easy/2015/07/16/9a619668-2b0c-11e5-bd33-395c05608059_story.html

¹⁰ https://www.washingtonpost.com/politics/the-6526-miles-of-fences-in-the-southwest-border/2015/07/17/e4e4e674-2c40-11e5-a5ea-cf74396e59ec_graphic.html ; http://www.globalsecurity.org/security/systems/mexico-wall.htm

¹¹ http://blog.mondediplo.net/2013-11-29-Et-la-frontiere-devint-un-marche-prospere-et ; http://usnews.nbcnews.com/_news/2013/06/21/19062298-price-tag-for-700-miles-of-border-fencing-high-and-hard-to-pin-down ; see also http://www.oxfordamerican.org/magazine/item/558-art-against-the-wall; http://www.cnbc.com/2015/10/09/this-is-what-trumps-border-wall-could-cost-us.html

¹² http://blog.mondediplo.net/2013-11-29-Et-la-frontiere-devint-un-marche-prospere-et ; http://usnews.nbcnews.com/_news/2013/06/21/19062298-price-tag-for-700-miles-of-border-fencing-high-and-hard-to-pin-down

¹³ http://www.bloomberg.com/news/articles/2010-09-15/idiotic-mexico-border-fence-cost-3-billion-does-nothing-dave-shiflett

¹⁴ http://www.zdnet.com/article/boeing-virtual-fence-30-billion-failure/

¹⁵ http://www.americanthinker.com/articles/2016/03/the_problem_with_the_wall.html

¹⁶ http://work.chron.com/salary-law-enforcement-border-patrol-person-3148.html

¹⁷ https://apps.cndls.georgetown.edu/projects/borders/exhibits/show/the-fence/political-implications ; http://www.reuters.com/article/us-usa-election-mexico-idUSKCN0W91WB

¹⁸ http://www.newsweek.com/2016/02/26/environmental-impact-us-mexico-border-wall-426310.html ; http://www.huffingtonpost.com/boonsri-dickinson/us-mexican-border-wall-de_b_419208.html

¹⁹ http://www.nytimes.com/2013/06/17/us/as-us-plugs-border-in-arizona-crossings-shift-to-south-texas.html ; http://www.azcentral.com/story/news/politics/immigration/2015/08/30/study-tighter-border-brought-az-mexican-migrants/71442296/

²⁰ http://cis.org/seminara/new-pew-report-confirms-visa-overstays-are-driving-increased-illegal-immigration ; http://www.usatoday.com/story/news/2016/01/19/immigration-visa-overstays-department-of-homeland-security-report/79026708/

²¹ http://www.people-press.org/files/2016/03/3-31-16-March-Political-release-1.pdf
http://www.dallasnews.com/news/politics/headlines/20160628-most-texas-voters-support-donald-trumps-border-wall-and-muslim-ban-poll-says.ece

²² Nieto-Gomez, Rodrigo. 2016, "Walls, Sensors and Drones: Technology and Surveillance on the US-Mexico Border." In Borders, Fences and Walls: State of Insecurity, Elisabeth Vallet, editor, pp. 191-210. Abingdon-on-Thames: Routledge, p. 204.

²³ https://www.whitehouse.gov/interactive-budget

²⁴ http://www.wsj.com/articles/mexican-immigration-to-u-s-reverses-1447954334 ; http://www.pewresearch.org/fact-tank/2016/04/14/mexico-us-border-apprehensions/ ; http://www.pewhispanic.org/2015/11/19/more-mexicans-leaving-than-coming-to-the-u-s/

²⁵ http://www.pewhispanic.org/2015/11/19/more-mexicans-leaving-than-coming-to-the-u-s/

References

http://news.nationalgeographic.com/2016/03/160304-us-mexico-border-fence-wall-photos-immigration/
http://www.globalsecurity.org/security/systems/mexico-wall.htm
http://content.time.com/time/photogallery/0,29307,1814377,00.html
http://map.walls.world/pages/home
http://www.toptenz.net/10-infamous-barrier-walls-throughout-history.php
http://www.history.com/news/history-lists/7-famous-border-walls
http://origins.osu.edu/connecting-history/top-ten-origins-walls
http://www.theguardian.com/world/ng-interactive/2013/nov/walls
https://www.kcet.org/shows/artbound/a-brief-history-of-border-walls
https://www.washingtonpost.com/news/the-fix/wp/2016/02/26/so-how-high-will-donald-trumps-wall-be-an-investigation/
http://www.pbs.org/weta/washingtonweek/blog-post/donald-trump-wants-build-wall-border-mexico-can-he-do-it
http://www.esquire.com/news-politics/a44782/donald-trump-the-wall/
http://www.cement.org/docs/default-source/th-paving-pdfs/concrete/types-and-causes-of-concrete-deterioration-is536.pdf?sfvrsn=4
http://www.rawstory.com/2016/06/the-problem-with-reinforced-concrete/comments/#disqus
https://theconversation.com/the-problem-with-reinforced-concrete-56078
http://10mosttoday.com/10-most-incredible-man-made-barriers/

http://www.zdnet.com/article/boeing-virtual-fence-30-billion-failure/

http://www.chron.com/news/houston-texas/article/1B-virtual-border-fence-went-from-optimism-to-1688076.php

http://www.bloomberg.com/news/articles/2010-09-15/idiotic-mexico-border-fence-cost-3-billion-does-nothing-dave-shiflett

A Sense of Wander

Pages

Wednesday, July 6, 2016

Something there is that doesn't love