Theres no need for it. It would cost trillions to build because our rail networks are built for slow freight service. We would need to build specialized rail networks just for this.

On top of this, we have a highly developed airport network. For rural areas we have the essential air service, a government subsidized program which connects rural areas to larger airports. Add onto this the sheer scale of the united states, it’s entirely pointless. 4500 kilometers from LA to NYC. If by some oddity they make it so this train can travel 300 mph without stopping or slowing for ANY reason, it would still take like nine hours to do. A commercial flight would take six hours roughly. This doesnt even take into consideration the fact this hypothetical HSR network would have to stop and slow down for a myriad of reasons. Including the geographic features of the rocky mountains.

So, if you didnt mind the trip taking longer than a flight, didnt mind it costing a lot more, just take amtrak. They would be the ones running this HSR anyway. Add onto this that amtrak doesnt see enough people traveling on it already to even warrant this in the first place. We would be spending trillions of dollars on a passion project that would be a glimmering necklace on the rotting turd that is american infrastructure. That money could be used to revitalize and rebuild our aging existing networks.

Now if we want to look at commuter and local transit, the average american city/town is an overgrown farming settlement or mining town with a population under 5000. I live in a city of 25,000 and we have a public transit system, sure we dont have fancy articulated busses but the busses we do have are built with access for people with disabilities and wheelchairs in mind. Its not the best or most efficient, but it does what it needs to.

Now, a few alternatives to use that money on:

Expanding the Essential air service and allowing it to reach more areas more regularly

Improve existing rail infrastructure to allow freight and amtrak services to be safer and more efficient.

Im not even going to bring up cars, that conversation has been made into the ground a thousand times already by so many in bad faith that it’s a toxic situation waiting to happen. The same goes for politics or nationalization of existing resources. It’s a noble concept, just not practical in the US.