Editing Snowpiercer (section)

===Class upgrade and social mobility===
Third Class Passengers and Tail section survivors represent 70% of the once 3,000 souls onboard Snowpiercer (approximately 2,100 persons).

There was a small measure of social mobility in Snowpiercer. While the Tail Section was apparently given compulsory contraceptives, what few children existed among the Tailies were sometimes recruited for an apprenticeship when a position needed to be filled, in skilled or unskilled labor, which is implied to open access to at least Third Class. After the death of Electrical Engineer Di Marco, [[Miles]] was promoted to an Engineering apprenticeship in the Engine Car, after attending Miss Gillies' Class and tutoring lessons by Melanie Cavill. He and several other Tailie children had previously been selected to move up train in what is suggested to be a once somewhat routine occasion where talented Tailie children were given the chance of a better lifestyle in exchange for their skills. The fact that Miles, a Tailie, was given such personal attention even before the revolution suggests that at least with the children, the train's staff didn't discriminate in cultivating their gifts.

Third Class Passengers once could apply to regular Fightnights which, while brutal, were nonetheless a means of progressing from Third to Second Class.

While once frowned upon by Thirdies, stable relationship between Third and Second Class passengers could lead to some sort of civil union and Class upgrade.

Under unknown circumstances, some Tailies have been able to move up train such as Zarah Ferami and [[Astrid]]. Astrid won an apprenticeship early in the journey. Zarah accepted an opening in the night car.

On rare occasions, Tailies had been known to be moved up train for special reasons: [[Old Ivan]] often recounted stories of a time when he was briefly brought forward to tune a piano, though he was later returned to the Tail. Andre Layton was offered a deal to become a Third Class passenger in exchange for his skills as a homicide detective, something that was lacking in the train's staff or other passengers.