[sokoloff]

If you had the high-speed train stop only at Gulfport (xor Biloxi) and maybe at Slidell, with regional service to pick up the small towns in between and take pax to the larger stations where they’d change to the faster train, you may be able to preserve a competitive Mobile to New Orleans time and still catch the intermediate city travelers. (This is a limited version of the airline hub-and-spoke to allow the trains to be faster door-to-door than driving, because if you can’t be better than driving in some obvious and personal way, many people will quite reasonably just drive the 140 miles on their own schedule and terms.)

[bombcar]

That's the hardest part - people will drive 6+ hours even when there are faster/better options if they need a car at the other end.

So transit between cites doesn't work as well until the endpoints are adequately transited themselves (or your destination is something like an airport where you can't bring your car anyway).

[ghaff]

At one point I was doing quite a bit of driving between New Orleans and a worksite in Pascagoula (just across the MS/AL state line from Mobile). This wouldn't have been very interesting at all given Pascagoula was very spread out and I absolutely needed a car once I was there. And it's a pretty straightforward ~2.5 hour drive.

Taking the train to NYC by contrast a car is, in general, actively a negative thing once you arrive.