• The tunnel ran for 4,309 feet from an entrance found near Tijuana to a sealed San Diego
  • It featured a complex power system, a railway for transport, ventilation and a drainage system
  • It's the 15th tunnel authorities have found running from California to Mexico since 2006

Authorities announced Thursday a 4,309-foot tunnel discovered in August running from San Diego to Tijuana was the longest smuggling tunnel ever found.

U.S. investigators had been working with Mexican authorities to map the tunnel after its discovery in the San Diego area. The tunnel entrance was near Tijuana. It is 5 1/2 feet tall, 2 feet wide, and about 70 feet underground. Its exit was blocked by several hundred sandbags.

An offshoot tunnel was found that ran for 3,529 feet. Investigators suspected its exit was plugged after becoming “unsustainable for whatever reason,” Border Patrol spokesman Jeff Stephenson said.

“This one blows past (the second-longest),” Border Patrol operations supervisor Lance LeNoir told reporters. “We never really thought they had the moxie to go that far. They continue to surprise me.”

The tunnel reportedly had a cart and rail system for faster transport, forced air ventilation, high voltage electric cables and panels, a drainage system, and an elevator at the entrance.

“The sophistication and length of this particular tunnel demonstrates the time-consuming efforts transnational criminal organizations will undertake to facilitate cross-border smuggling,” Cardell T. Morant told reporters. Morant is the acting special agent in charge of U.S. Immigration and Customs Enforcement's Homeland Security Investigations unit in San Diego.

It’s the 15th tunnel authorities have found running between California and Mexico since 2006, all of which used some form of railway system, ventilation, hydraulics and lighting. The previous longest tunnel was also found near San Diego in 2014 and ran for 2,966 feet.

No arrests have been made, but investigators suspect the tunnel was used by the Sinaloa Cartel, which has a reported stronghold in the area where the tunnel was found.

“As efforts to strengthen security on our Southern border increase, Mexican drug cartels are forced underground to smuggle their deadly drugs into the United States,” DEA Special Agent in Charge John Callery told reporters. “The sophistication of this tunnel demonstrates the determination and monetary resources of the cartels.”

border patrol photo
An undocumented immigrant is pictured being bodysearched by a U.S. Border Patrol agent after being caught hiding in a sugarcane field near the U.S.-Mexico Border on June 12, 2018 near Mission, Texas. John Moore/Getty Images