Watch CBSN Live

Why it would be hard to build a border wall

Trump backs away from national emergency

The border wall is more than just a proposed barrier between the U.S. and Mexico; it was central to President Trump's presidential campaign, and the obstacle in the way of ending the longest government shutdown in American history.

But while "build the wall" is a simple catchphrase, the logistics of doing so are complex. Much of the border is composed of rugged terrain, with a combination of deserts, mountains and rivers demarcating the line between the two countries.

If Mr. Trump obtains the funds to build the wall, either through an appropriations bill passed by Congress or calling a national emergency, the wall isn't the only thing that will need to be constructed: Some of the border is so remote that the government would have to build new roads to get there, according to a Defense official.

At the easternmost part of Texas, where the Rio Grande empties into the Gulf of Mexico, there are no fences, and the nearest road is three miles away. The U.S. side is a wildlife area, relatively close to a beach resort.

Due to the rugged terrain elsewhere on the border, particularly the more mountainous areas in the west, the closest border roads are dirt paths carved by border patrol agents.

The wall would also slice through several wildlife reserves and state and national parks. In October, the Department of Homeland Security released a memo proposing 17 miles of new construction of a border wall, which would waive several environmental regulations. According to the Center for Biological Diversity, those plans would cut through several wildlife refuges and the National Butterfly Center, as well as private farms.

The proposed wall would also cut through national parks, such as Big Bend National Park in Texas, which contains very few roads. Along with being natural reserves, these parks are not very accessible for transportation of wall construction material.

The inaccessibility of the border is only one challenge to its construction. According to the Defense official, the federal government controls only 400 miles of the border. The remainder is private property. It could take six to nine months for the government to declare eminent domain, which is the power of the federal government to take private property for public use. It is likely that proclaiming eminent domain would also face legal challenges.

Furthermore, even if a wall were to be built, drug dealers often find other ways to get drugs into the U.S., such as smuggling them through entry points or building extensive tunnels. When Mr. Trump visited McAllen, Texas, last week to visit border patrol agents and discuss border security, they expressed support for the wall. However, the border patrol agent in charge showed an image of a tunnel illegal immigrants had carved — under a wall.

Despite the potential logistical difficulties presented by building a wall, not to mention funding challenges should he declare a national emergency, Mr. Trump remains firm that a border wall is the only way to truly secure the border.

"The Steel Barrier, or Wall, should have been built by previous administrations long ago. They never got it done - I will. Without it, our Country cannot be safe. Criminals, Gangs, Human Traffickers, Drugs & so much other big trouble can easily pour in. It can be stopped cold!" he tweeted last week.