40 days of packed trains

This winter, from January 13 until February 21, nearly every train cabin in China looks like this — standing room only — as the nation celebrates the Spring Festival to mark the Lunar New Year. The yearly 40-day period, which shifts depending on the lunar calendar, also marks the world’s largest human migration, as hundreds of millions of workers and students travel home to the countryside to reunite with family, then travel back to the cities after the holiday.