High speed rail is a non-starter in the US, except for in certain regions. It's 2000 miles from Chicago to LA. Optimistically, if you had a train that averaged 200 miles an hour, it would still take 10 hours. That's just not competitive.
However an average speed of 200 miles (320 km) per hour is still a lot. Especially because you will have stops in between which of course means that the v_max must be even higher.