Going coast-to-coast in the US on rail would take a long time, even with a bullet train, so it just wouldn't be competitive with airplanes.
However, going up and down the coasts would make perfect sense for HSR. Traveling from LA to SanFran, for instance, would be much better on a bullet train than an airplane, and the travel time would probably be similar (airplanes have lots of wasted overhead time). The northeast corridor would also be a great place for a bullet train (no, the Acela is not a bullet train). NY-Chicago or DC-Chicago would probably be a good route too.
The problem in the US is just a total lack of political will, and an idiotic aversion on the part of the populace to using trains.
However, going up and down the coasts would make perfect sense for HSR. Traveling from LA to SanFran, for instance, would be much better on a bullet train than an airplane, and the travel time would probably be similar (airplanes have lots of wasted overhead time). The northeast corridor would also be a great place for a bullet train (no, the Acela is not a bullet train). NY-Chicago or DC-Chicago would probably be a good route too.
The problem in the US is just a total lack of political will, and an idiotic aversion on the part of the populace to using trains.