The Great Wall of America

The US is erecting miles of new fences along much of the Mexican border. Can a barrier stop the tide of illegal aliens?

Anthony Suau for TIME

West of Naco, Arizona, some immigrants, including a 10-year-old boy, scale the new border fence in an effort to reach the States.

The smuggler was surprised to see us. It's his business to monitor traffic along his stretch of the border, and he had just watched from his hiding place as a white-and-green patrol truck rolled slowly past on the U.S. side. The day shift was ending for "la migra," the border patrol, so it was time for him to move.

He urged his clients--11 illegal aliens--to get over the fence quickly. Within minutes, all were safely across the border about five miles (8 km) west of Naco, Ariz.--roughly the same spot where Coronado and his conquistadores made the first recorded crossing in...