3/4/2016 National Geographic
The candidates for president of the United States, particularly on the Republican side, have hotly debated how to handle the roughly 2,000-mile (3,200-kilometer) border between the United States and Mexico.
Donald Trump has famously and repeatedly promised to seal the border with a wall if he’s elected. He and others have promised to send people who illegally crossed the border—a number that appears to have leveled off—back to Mexico. For these people, the border wall isn’t an abstraction. Many parts of the border are already covered in fences. In other spots, the wall is not made of bricks, but out of scanners, drones, and guards.