Wiki is lying, the top speed of any train in the US is 150 mph.
If you can remember where you got that number I'd appreciate you posting it.
This isn't a matter of doubting you. I want to know who's saying what and when numbers are different I like to know why - what assumptions they are making, etc.
Here you go....all the train records fit to print. Knock yourself out.
Train Speed Records: The Fastest, Longest & Heaviest Trains