High Speed Rail in the USA

[Brown, Jon Brow]

I just did a quick search.
Washington DC to Detroit, Michigan via AMTRAK is 13 1/4 hours and costs $183. Via Southwest Air its $165 and 4H 20M (that's a plane change, didn't quickly see a direct flight).
Washington DC to Atlanta Georgia via AMTRAK is $116 and 13 3/4 hours. Via Southwest its $124 and 1H 50M (direct flight).

You are correct that travel anywhere within the very heavily populated northeast corridor is probably better by the train, however that most definitely does not apply throughout the rest of the country. Both of the ones just above are about your 500 mile distance and here those are relatively short hops.

With journey times of half a day of course people are going to fly instead.

But the point I'm making is that why in the worlds wealthiest nation are the railways so far behind Europe, China and Japan. Journeys of that distance should only take 2-3 hours by train, which is quicker than flying when you take into account airport check-in.

Some rail routes in America are slower now than they were in the 1920s!