I misread the comment as Boston-New York like the route in the article. Boston-New York is slower than the rest of the route. South Station in Boston to Penn Station in New York takes 3:46[1] and those stations are 212 miles apart[2] which is an average of about 55 mph.
[1] https://www.amtrak.com/content/dam/projects/dotcom/english/p...
[2] https://www.google.com/maps/dir/Pennsylvania+Station,+New+Yo...