Regarding the article, I'd like to see them plot the rate-of-change: how long it took to go from a month to a week to a day and so on, and then continue it into the present day. I think we've hit something of a cap on speed.
Not necessarily. IIRC, outside of the East Coast corridor, the rails only allow the trains to go ~35mph. There are also high-speed / bullet trains as well, none of which are available in the US (for now).
And inside the East Coast corridor, regular bicycles are prohibited on all Amtrak trains at all times. I would literally pay an extra $50 per bicycle round trip if they offered it, but they do not. Oh, and the train from NYC to Montreal runs slowly, which gives it an ideal duration for a night service, but none is ever offered. You have to do the 12-hour trip during the day, which for working people is nonsensical.
Regarding the article, I'd like to see them plot the rate-of-change: how long it took to go from a month to a week to a day and so on, and then continue it into the present day. I think we've hit something of a cap on speed.