Customs officials said the pot haul, one of the largest ever made at the El Paso port of entry, would be worth $10 million on the street.
"The anti-terrorism exams that U.S. Customs inspectors are now conducting led to this seizure," said U.S. Customs Service El Paso Port Director David Longoria.
Drug seizures have been up on the Texas border since new anti-terrorism inspections were initiated along the U.S-Mexico border.
An inspector told the driver to open the back doors of the trailer for a visual examination of the contents. Merchandise was stacked to the ceiling so the inspector ordered an X-ray examination.
Customs inspectors operating the X-ray system noticed a "dense area" within the trailer and directed the vehicle to the inspection dock for a thorough exam. They found numerous boxes that were different than the boxes of Christmas trees. A total of 1,964 marijuana-filled bundles were seized.
The driver ran on foot to Mexico and no arrests were made but an investigation is continuing.
The seizure is one of the largest ever at El Paso.
On May 2, 2000, inspectors seized 11,542 pounds of marijuana at the Ysleta cargo facility. Customs inspectors also seized 9,367 pounds on April 20, 2001, and 8,320 pounds on Aug. 27, 2001.
The largest marijuana seizure ever made at El Paso was in the 1980s when inspectors seized about 14,000 pounds hidden in a tanker-trailer.