His may be the loudest voice on the topic, but a certain real estate mogul with interesting hair isn't the only one thinking about walls. Whether it's to guard against external enemies or stem a tide of undocumented immigration, policymakers and talking heads in countries around the globe are turning to an age-old solution: Build a gigantic wall, they say, or at least some sort of barrier that makes it more difficult to cross the border.
Just how effective physical barricades can be remains a topic of hot debate. Much less ink has been spilled over other basic questions about building a wall, like: Can it be done? What would it look like? And how much is it going to cost?
Unlike the centuries of old when men built walls of stone by hand, modern border barriers usually come in the form of a fence. Although these chain-linked blockades may be easier to erect than their rock-based forebears, they also come with a pretty hefty price tag (and that's saying nothing of the political barriers such a construction faces).
National Walls in History
It was all the way back in 220 B.C.E. when Chinese Emperor Qin Shi Huang set out to erect the country's Great Wall by linking together existing structures along China's northern border. The 13,000-mile (20,921-kilometer) barricade that still attracts throngs of tourists to this day was originally meant to keep people out rather than draw them in. The wall was designed to repel attacks from outside tribes.
Roman Emperor Hadrian had a similar notion in mind in 122 C.E. when he ordered his men to build a 73-mile (117.5-kilometer) wall in the south of Scotland to help protect the empire from its enemies. The project took 15 years and thousands of tons of stones to complete. Stretches of that wall – and remains of the fortresses that dotted it – can still be found scattered like a raggedy belt across the United Kingdom's midsection.
Border Fences Today
When folks talk these days about building a "wall" along the southern border of the U.S., or in the various European countries faced with a flood Syrian refugees (or around the Hollywood movie studios that for some reason continue to allow Nic Cage to make movies), what they're really often talking about is some sort of tricked-out fence rather than a Berlin Wall-style structure. The idea behind the barriers is to slow down people, cars, trucks, tanks, and just about anything else that attempts to cross the border.
Just look at Saudi Arabia. The oil-rich Middle Eastern kingdom is fast at work on a 600-mile (966-kilometer) fence along its northern border with Iraq to shield against potential attacks from Islamic militants. The blockade features sand embankments, a pair of chain link fences topped with razor wire and a separate barbed wire hurdle. Meanwhile, a smattering of cameras, underground censors and watchtowers are meant to both dissuade visitors and alert authorities to their presence.
The Saudi fence is strikingly similar to what inmates looking to escape a U.S. prison are likely to run into before they get off the grounds. Staggered layers of razor ribbon fencing 10-12 feet (3-4 meters) high are the standard for incarceration facilities across the U.S., along with electrified fences that will make most jailbirds think twice about trying to scale them.
In an effort to also keep contraband like drugs and weapons flowing in and out of the facilities, many prisons also draw on cameras, microwave detection systems and motion sensors. The result is a highly monitored buffer between the prison itself and the free world outside.
Barriers like that ain't cheap, especially when they're expected to cover an area as expansive as an international border.
Nearly 700 miles (1,127 kilometers) of fencing already dot the U.S.-Mexico border. The Rio Grande River also provides a natural barrier of sorts along southern Texas. But if policymakers really want to fence off the entire border – not to mention the northern perimeter – it's going to cost them. The U.S. spent $2.4 billion over three years to build 670 miles (1,078 kilometers) of fencing in California and Arizona, according to the Government Accounting Office.
The country shares roughly 6,000 miles (9,656 kilometers) of international borders to the north and south. Based on the costs already incurred, Uncle Sam could expect to fork over at least another $19 billion to cover the tab just for construction costs, and then there are issues of needing to buy border-adjacent private property from citizens who own it.
And that's all if building a wall were something the country actually wanted to do.