However, US officials in a number of cities moved to downplay or dismiss the billionaire's suggestion
Officials in the US have denied that billionaire Elon Musk has received “verbal approval” to build a Hyperloop transport system serving New York, Philadelphia, Baltimore and Washington DC.
Hyperloop is a new technology that has been proposed by the SpaceX and Tesla founder in recent years.
The concept would see passengers travel in pods at very fast speeds (average speeds of around 970km/h) within a sealed tube.
Musk and SpaceX have made their initial design open source, and a number of companies are attempting to bring the concept to life. One company, Hyperloop One, is currently conducting trials at a dedicated test track in Nevada.
In a tweet yesterday evening, Mr Musk appeared to suggest a full-fledged Hyperloop system could be on the way, and would dart between New York and the US capital - more than 300km away from each other - in only half an hour.
Just received verbal govt approval for The Boring Company to build an underground NY-Phil-Balt-DC Hyperloop. NY-DC in 29 mins.— Elon Musk (@elonmusk) July 20, 2017
Officials in the cities involved quickly shot down any suggestion that approval had been granted.
A spokesperson for the NYC mayor said:
In comments quoted by The Guardian, a spokesperson for the city of Philadelphia said: "Elon Musk has had no contact with Philadelphia officials on this matter.
"We do not know what he means when he says he received ‘verbal government approval’. There are numerous hurdles for this unproven ‘hyperloop’ technology before it can become reality."
However, a White House spokesperson confirmed to Bloomberg that their officials had had “promising conversations to date” on the prospect of a Hyperloop.
Mr Musk - whose Boring Company is working on future transport solutions, with a focus on tunneling - quickly moved to clarify his initial suggestion, tweeting: "Still a lot of work needed to receive formal approval, but am optimistic that will occur rapidly.
"If you want this to happen fast, please let your local & federal elected representatives know. Makes a big difference if they hear from you."