Workers at warehouses just feet from the U.S-Mexico border would come and go at odd hours. Few, if any, knew what their trucks carried.

Few knew, too, that the buildings sat atop the openings for two of the longest, most sophisticated tunnels ever built to smuggle drugs from Mexico to the United States.

"Look over there across the street, I have no idea what they do," said neighbor Mario Rodriguez, 46, pointing to a large warehouse with no trucks outside.

npr.org
cbs8.com
mydesert.com
old zack