It's literally how Japan operates as a world power despite being about the size of California.
It's a pretty easy system to implement with the right leadership and engineers. It would basically just need to act as a wheel and spoke type of system. There are catches as the shape of the country is a little odd. But it could be implented. You should be able to travel from Portland Maine to Portland Oregon without a flight.
Right now your options are drive for literally 2 full days, take grey hound buses for literally 4 full days or flight. WHich means you only really have one option. In a theoretical high speed rail you could take a train from Portland to NYC in a few hours, NYC to LA on express (basically hitting Chicago, Denver, Cleveland and a handful of big cities as it races across the US in about 13 hours, then up the coast in another 8 or so hours. So basically a full day of travel, not as fast as a plane, but it still is a better option than most.
Keep in mind I have little skin in the game, high speed rail gains me little other than an option to go home without traffic perhaps, as I'd at best be lucky if a rail stop hit Burlington Portsmouth or Manchester.