“We could apprehend anywhere between 100 and 200 a shift,” said Mark Foster, a Border Patrol supervisor. “On the weekend its very hard to get all the incursions dealt with, with the manpower that we have.”

In response to the increased traffic the Border Patrol is shifting more manpower and resources, like night vision technology and mobile towers, to South Texas. By the end of this year the Rio Grande Valley Sector expects to have 600 more agents.

Even with a record amount of manpower and infrastructure along the entire southern border, the Rio Grande Valley has the fewest number of agents per mile compared to other places. It also has the least amount of fencing. In some places the only deterrent is a few ground sensors.

The terrain adds to the challenge of patrolling this section of the border. The Rio Grande swerves and curls downstream like a string of yarn. Access is limited by gravel pits, cliffs and delicate wildlife refuges. There are also private residences and farmland, where locals can make a pretty profit cooperating with smugglers.