As of August 2022, the fastest train on Earth, based on its record speed, is the Japanese L0 Series Maglev with a record speed of 603 kilometers per hour.
Why does the US not have fast trains?
The interstate highway system cost $129 billion — roughly $290 billion in current dollars — and took 35 years to complete, running from 1957 to 1992. The $1.2 trillion infrastructure bill enacted in 2021 has $102 billion for rail, but none of the money is set aside for high-speed rail.