PHOENIX — Authorities say they've found an unfinished tunnel stretching from Mexico to Arizona that appears to be “the most sophisticated tunnel in U.S. history."
Federal officials said Thursday the tunnel intended for smuggling ran from a Mexican neighborhood to San Luis, Arizona.
They say it had a ventilation system, water lines, electrical wiring, a rail system and extensive reinforcement.
Homeland Security Investigations found the tunnel Tuesday.
Investigators don’t know what exactly the tunnel would have been used for because it was incomplete, but smugglers have been using tunnels to get drugs and people across the border for decades.