The US is really really big. “Long distance” in the US is mind boggling compared to Japan. Also there are many population centers and they are evenly distributed. Again, using Japan as an example, You can draw an arc from Sendai to Tokyo to Osaka and hit the major population centers. Try doing that with Boston to Chicago to LA … what happened to Houston? New York? Miami?
There is a big counterexample: Washington (Norfolk) to Boston. And if you are traveling city center to city center rail is cheaper. But Amtrak isn’t dumb and prices the good trains just below air. BTW Japan Rail isn’t dumb either and Bullet Train tickets can reach airfare levels.
Tokyo to Osaka is about 500 km. That is the same as the distance from Boston to Philadelphia. And that is not “long distance” in the US. In addition that corridor of Japan has a much larger share of Japan’s economy than the Boston-Philadelphia corridor.
There are some historical reason we don’t have bullet trains even where they make sense. But overlaying scaled maps can help you understand a lot.
I use Japan because I know the country well. I travel for business in the US. And I am forever explaining to my Japanese colleagues why we can’t “just visit” a customer when something goes wrong.
Latest Answers