In late 2016, in an impressive sublimation of traffic-caused road-rage, Elon Musk announced via Twitter that
Am going to build a tunnel boring machine and just start digging...
It shall be called "The Boring Company"...
I am really going to do this.
Per early-2017 reports, Musk has now acquired a tunnel-boring machine, started digging a tunnel near his LA SpaceX office, and is investigating improvements in mining technology. The vision is to eventually have many kilometers of tunnels under cities, as well as provide much better tunneling for hyperloop transportation systems.
This is arguably more progress, albeit with less of a potential pot of money, than another massive infrastructure project (probably) announced via Twitter: Trump's border wall. As of early 2017, there are very preliminary plans, but no proposal submitted to congress.
In a separate question we ask how much wall will be built. Here, we'll put these projects head-to-head:
By 2025, Will The Boring Company dig more tunnels (by length) than Trump's Mexican Border Wall?
Tunnel length will be counted as dug-out (but not necessarily finished) tunnels built by the Boring company or any other entity substantially under the control of Elon Musk. Wall length will be counted as per the associated question – note in particular that fence does not count.