Low train fare in comparison to air fare in the past. Now, air-fare is affordable but people still like traveling by train. I am writing about Russia. USA also has large territories. It's difficult to imagine Hungary or Romania operating domestic airlines. The territories of the countries are too small.What are the changes necessary in US history after the 19th century to make rail ridership in the US per capita as high as say, Russia, Poland, or Spain? I know that low population density for the US has often been cited as a reason, but this does not explain low rail ridership for Amtrak east of the Mississippi, where the population density is relatively high, and where population density resembles Russia East of Urals, or countries like Spain, Poland, and the Balkans, which also have relatively low population densities compared to Western Europe, but have significantly higher rail ridership per capita compared to the Eastern part of the US.
And a good rail network.