I'm always confused by the high-speed rail numbers. Exactly how many trains would it take to get 2/3 of the US population using rail? Take the average international-sized airport runway. It can land a 747 every couple minutes. That's hundreds of people every minute. A high-speed rail line cannot take even a fraction of that number. The trains cannot run at speed without significant time/distance between them. That's…
A Shinkansen line (arbitrarily chosen because it was the first thing that popped up in my search) can do 13 trains per hour with 1,323 passengers per train, which is equivalent to one 747 every 1.4 minutes.
I'd have to see the math, but there is also a question as to carbon emissions per-passenger/distance. I believe that on long flights (more time at high altitude) widebody aircraft might be more fuel efficient than high-speed trains stuck on tracks.