If Elon Musk’s Boring company makes a New York City to Washington DC hyperloop tunnel, then it would be 226 miles long. This would be nearly three times longer than the current longest tunnel.
Elon Musk tweeted out that he has been given verbal approval by someone in the US government to build a New York to DC hyperloop tunnel.
Here is the wikipedia list of longest tunnels.
The Gotthard Base Tunnel (GBT) is a railway tunnel in the heart of the Swiss Alps expected to open in 2016. With a route length of 57 km (35.4 mi) and the tunnel system totals 151.84 km (94.3 mi) of tunnels, shafts and passages. It is the world’s longest rail tunnel, surpassing the Seikan Tunnel in Japan.

Brian Wang is a Futurist Thought Leader and a popular Science blogger with 1 million readers per month. His blog Nextbigfuture.com is ranked #1 Science News Blog. It covers many disruptive technology and trends including Space, Robotics, Artificial Intelligence, Medicine, Anti-aging Biotechnology, and Nanotechnology.
Known for identifying cutting edge technologies, he is currently a Co-Founder of a startup and fundraiser for high potential early-stage companies. He is the Head of Research for Allocations for deep technology investments and an Angel Investor at Space Angels.
A frequent speaker at corporations, he has been a TEDx speaker, a Singularity University speaker and guest at numerous interviews for radio and podcasts. He is open to public speaking and advising engagements.