At 85 miles long, it is the longest tunnel in the world and supplies 1.3 billion gallons of water daily. However, it also leaks 35 million gallons daily and has been leaking for decades.

The tunnel originates in Tijuana, Mexico, near the Otay Mesa Port of Entry and extends a total of 4,309 feet long -- more than three-quarters of a mile.The next longest tunnel in the U.S ...

The second-longest tunnel in the U.S., discovered in San Diego in 2014, extended 2,966 feet, the Border Patrol said. During fiscal year 2019, the San Diego sector seized 3,273 pounds of marijuana ...

Border patrol chiefs were taken aback by the scale of the tunnel, which is far bigger than the previous longest – a 2,966ft passageway found in San Diego six years ago.

Tap to read about longest tunnels in the world. Delaware Aqueduct, USA This 137-kilometer water tunnel supplies New York City with water, making it the longest continuous tunnel in the world.