NEW YORK (CBSNewYork) — Seventy-nine years ago Thursday, the very first tube of the Lincoln Tunnel, connecting New Jersey and New York City, opened to traffic.

Building the mile-and-a-half-long structure above ground would have been no small accomplishment, but to build it under the Hudson River was a monumental task, CBS2’s Dana Tyler reported.

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It took three years and seven months to complete the center tube of the tunnel, a much-needed route to handle a mounting tide of traffic, according to an education video issued by the Port Authority.

Workers digging the tunnel were known as “sandhogs” and had to undergo physicals to make sure their hearts and lungs could handle working in the compressed air chambers under the water.

Hundreds of huge iron rings, each weighing 21 tons, were assembled and bolstered together on-site, forming the lining of the tunnel.

While one crew worked from the Jersey side, another crew proceeded toward them from the New York side. Alignment of both ends vertically and horizontally took considerable engineering skill.

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The first “hole through” was achieved on Aug. 3, 1935.

During the construction process, engineers experimented with different ways to get the deadly exhaust fumes out of the closed tunnel. The result is a system that ventilates fumes through the ceiling and pumps fresh air in from the curb.

And on Dec. 22, 1937, the world’s first mechanically ventilated underwater tunnel was open to traffic.

The Port Authority went on to open the north tube of the Lincoln Tunnel in 1945 and the south tube in 1957, for a total of 13 toll lanes.

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The toll when the tunnel first opened was 50 cents per passenger car.