According to Gemini this hypothetical train would take about 18 hours.
It would also cost hundreds of billions of dollars and a decade to build.
Doesn't do much for seeing Uncle John next Tuesday.
I like trains. I like them a lot. But they don't work over long distances. Particular when you have dozens of state and city jurisdictions to cross.
Each of them get a vote.
Honestly I'd be happy just to have quality HSR on the East Coast. Boston to Richmond takes like 12 hours right now.
Maybe the West Coast could get a Seattle to San Diego route.
What's your source for this? I take this flight a lot and I find it hard to believe it's more than 5.5-5.75 on average. Looking at the last few weeks for one of them[0] supports my experience.
Maybe your number has TSA/airport time included.