File photo: US-Mexico border wall. Photograph:( AFP )
Mexican officials identified the entrance of the tunnel in August; tunnel is 5.5 feet high and 2 feet wide at a depth of 70 feet (21m) below the surface.
A passageway connecting the San Diego area in California to an industrial site in the Mexican city of Tijuana was found recently by US Customs and Border Protection. The tunnel stretches for 4,309 feet (1,313 metres) and has a lift, rail track, drainage and air ventilation systems, high voltage electrical cables and panels.
Authorities have refused to comment on potential suspects behind the tunnel, no drugs have been found in the tunnel and no arrests have been made.
There could exist a possible link between the tunnel and Mexico's Sinaloa cartel, which operates in the area and has been described by the US as one of the largest drug-trafficking organizations on the planet. Founder and leader of the Sinaloa cartel Joaquin "El Chapo" Guzman, is currently serving life at ADX Florence.
Mexican officials identified the entrance of the tunnel in August and US investigators mapped it before releasing the findings. The tunnel is 5.5 feet high and 2 feet wide, resting at a depth of 70 feet (21m) below the surface. US Customs and Border Protection are not clear how long it took to build it.
[ US officials say they have discovered the longest smuggling tunnel ever found on the border with Mexico. (Courtesy: Reuters) ]
Blocking a suspected former exit of the tunnel in San Diego's Otay Mesa industrial warehouse area were several hundred sandbags, as per reports. The main tunnel had an incomplete offshoot. The second-longest tunnel found in the San Diego area of the country in 2014 was 2,966 feet long, as per reports.
Impeached US President Donald Trump has asserted the need for a border wall many times, adamant that it is required to tackle illegal immigration and drug trafficking. Officials have concurred that most drugs are smuggled through legal ports of entry and hidden in privately-owned vehicles or transporter lorries mixed with other goods. A border wall would be as effective against a network of smuggling tunnels as a gun.