The fascinating animated series Half as Interesting took a look at passenger train service around the world, noting that the tracks in different countries are of different widths, which makes continental train travel more difficult. He also notes which routes serve the longest distance. This includes the legendary Trans-Siberian train from Moscow to Beijing, which is the third longest passenger route.
The world’s second longest train service is, big surprise, also in Russia. It’s also a Trans-Siberian service from Moscow to Vladivostok in a hundred and forty four hours and five thousand seven hundred and seventy two miles but the longest train service goes to the least friendly Korea in the world, North Korea. …the North Korean state railway runs this service from
Cheongyang to Moscow by sending this sleeper car north to the border to Russia and then attaching it to the Russian train from Vladivostok to Moscow