A hole leading to the tunnel was made in a concrete floor in the kitchen of an abandoned KFC restaurant.
The passage, most likely, was built just a few months ago. Its length is 180 meters (551 feet), it was located at a depth of about 6.5 meters (21 feet).
It is noted that from the US side the hole was only 20 centimeters (7.8 inches) in size. On the other side, the tunnel surfaced under a bed in a house in the city of San Luis Rio Colorado, Mexico.
The total weight of the drugs found in the car was 168 kilograms (370 pounds), including 118 kilograms (260 pounds) of methamphetamine, six kilos (13 pounds) of cocaine, three kilos (6.6 pounds) of fentanyl and 19 kilograms (41 pounds) of various types of heroin.
The tunnel will be filled with concrete at the end of the investigation.
It's the fifth tunnel found since 2007.