Keeping in mind what makes sense, all one has to do is study the results Amtrak gets with Acela. While many advocacy pundits look at miles traveled, the realistic pundits look at elapse times.
https://en.wikipedia.org/wiki/Acela_Express
NY to DC averages 2.75 hours elapse time over 225 miles achieves 75% market share
NY to Boston averages 3.5 hours elapse time over 231 miles achieves 54% market share.
The market share being limited to just trains and planes, completely ignoring buses and private vehicles.
It was not the additional 6 miles that lowers the NY to Boston market share 21% lower than the NY to DC market share, it was the additional 45 minutes of elapse time.
Which reinforces the idea that trains are really competitive with routes of less than 3 hours.
Anther consideration to account for is how congested the highways are. In the higher density areas of the NEC and California, the attractiveness of trains are much higher than in the less dense areas found in the rest of the country for travel of less than 3 hours.