From the air it all seems so calm—children play in the water while others live in houses just across the Rio Grande. The river forms the border here between Mexico and the United States.

To the south, the state of Tamaulipas has become perhaps the worst place in Mexico. A state filled with blood in a war between the Gulf Cartel and the violently notorious Zetas. To the north lies the Rio Grande Valley, a beautiful agricultural landscape with cotton, maize, and sugarcane growing everywhere. But it has also become one of the main drug smuggling routes into the U.S., with vans packed full with hundreds of pounds of drugs constantly make their way north.

At times, these attempts are picked up by law enforcement. Making a break for the river while radioing their bosses on the south side, these mules (a term for cartel drug carriers) show a vast understanding of the weaknesses of U.S. law. The bold cartel members wait on the U.S. side of the river to try and fight for their load of drugs as law enforcement agents watch helplessly, unable to do anything but watch.

Shaul Schwarz is an award winning photographer and filmmaker. Schwarz, a TIME contract photographer, is represented by Reportage/Getty Images. Schwarz’s work has also appeared in major publications such as National Geographic, The New York Times Magazine and Paris Match, among others. Some of the most important honors Schwarz has received over the years include the Robert Capa Gold Medal, two World Press Photo Awards and the acclaimed Visa D’or in Perpignan.

Previously, Schwarz covered the January 2010 Haitian earthquake for TIME.