As American lawmakers argue over whether to fund a wall along the United States’ southwestern border, the federal government is moving ahead with plans to replace some of the fencing it built there years ago with 30-foot-tall steel bollard walls. Meanwhile, a growing number of countries worldwide have built border walls and other barriers to try to control the flow of people and goods.

There are a total of 77 border barriers worldwide — up from 15 at the end of the Cold War, Elisabeth Vallet, director of the Center for Geopolitical Studies at the University of Quebec-Montreal, told USA Today in 2018. Vallet and a number of other scholars in the field have spoken out against man-made barriers, arguing they are expensive and dangerous and questioning their effectiveness. Several of those scholars weighed in with essays published in a recent issue of the Journal of Latin American Geography.

Here in the US, the Department of Homeland Security (DHS) has erected more than 650 miles of fence and other types of barrier along the almost 2,000-mile US-Mexico border. Even before President Donald Trump took office, federal law required the barrier to be expanded by another almost 50 miles. In December, DHS announced that it had completed most of a $292 million project to build 40 miles of steel wall to replace “an outdated and operationally ineffective barrier” in the San Diego, El Centro and El Paso sectors of the border.

Lawmakers have until Feb. 15 to reach a compromise on a new border security plan or there could be another government shutdown. Disagreement over funding — Trump wants $5.7 billion in border wall money — led to a 35-day shutdown that ended Jan. 25, 2019.

To help journalists understand this issue and put it into context, we’ve pulled together academic studies, federal government reports and other scholarly literature. Below, we have summarized research that explains what border barriers are, why they have become so popular and whether they actually help countries control their borders. We have also included research that investigates the consequences of building these barriers, including impacts on the environment and local communities.

It’s important to note that government officials, politicians, scholars and others tend to use the terms “fence,” “wall” and “barrier” interchangeably when discussing man-man structures built to control a country’s borders. There also is some confusion over terms such as “border security.” New York Times reporter Glenn Thrush wrote an article offering a “glossary of the border debate.”

————————————–