Hyperloop approved between NYC and DC, says Elon Musk

Elon Musk says he has 'verbal' okay to build multi-state underground Hyperloop

But his phrasing, "verbal govt approval", is vague - especially for such a wildly ambitious undertaking. The train will transit between all the city centers, says his tweet.

A time comparison of Hyperloop and other modes of transport from San Francisco to Los Angeles. The experimental transportation method would shoot pods through underground tunnels at speeds of over 700 miles per hour (1,100 km/h).

Beyond the Hyperloop system, Musk has made plans to send two private citizens around the Moon and land an unmanned spacecraft on Mars by 2020.

Hyperloop would use the electromagnetic propulsion and magnetic levitation (mag-lev) technology, which is still experimental. The tunnels for tubes for the train will take as little as 3 meters in diameter, occupying less space than the underground conventional rail system. Philadelphia's deputy communications director Mike Dunn told us in an email that Musk hadn't contacted any Philadelphia officials about the Hyperloop and that there are many hurdles for this "unproven" technology before it can be implemented.

At the very least, the tweets showed Musk is still engaging with the White House. He first developed the ultrafast hyperloop in 2013.

Musk isn't willing to stop with NY and D.C. The billionaire entrepreneur continued to tease his plans on Twitter, replying to another user asking about a potential hyperloop system in Texas.

The Boring Company started as a joke, but became increasingly serious as Musk began tunneling in Los Angeles.

Boring Company, which was born out of Musk's frustration with traffic, aims to create tunnels to reduce auto congestion. Such a project would undoubtedly cost billions of dollars and require approvals, and likely funding, from federal, state and local officials to move forward.

That suggests that the safest, most efficient way to build the Hyperloop would be in straight lines.

De Blasio's press secretary added that the entirety of what they know came from Musk's tweet, and that's not how they evaluate projects of any scale.

Of course, verbal government approval, even if it's from coming from a sitting USA president, or someone within the Trump Administration, only bears so much weight.