I have worked with many immigrants from Mexico and other Latin countries for many years. I have had many discussions with them, especially concerning the drug cartels.
Many have talked about "The Tunnel".
This falls into a rumor. No evidence to back it up. Just hearsay.
The Sinaloa cartel had built a true tunnel from Mexico to the U.S. They played the long game. They started over 50 miles deep in Mexico. In a town with warehouses, they dug 500 feet down. They tunneled to a spot over 100 miles inside the U.S., to another town with warehouses.
This seems preposterous. The cartel has the money to pay for this. Engineers, surveyors, geologists, and slave labor.
"El Chapo" Guzman is crazy enough to do this. I've watched many docs and interviews with him to believe a possibility of a tunnel like this true.
If they built this behemoth with twin rail tracks allowing goods to travel back and forth, then drugs will always get into the U.S.
On the other hand, it might be misinformation from the cartel to make the U.S. go crazy looking for a phantom tunnel.