The world’s largest human migration, China’s Spring Festival travel rush, could date back more than 2,000 years and reflects the history and development of China’s transport networks. This year’s Spring Festival rush, or chunyun, takes place from February 2 to March 13, and is expected to produce a total of 9.5 billion passenger trips. The chunyun is believed to first appear along with the invention of the term guo nian, or spending the New Year, in the Zhou dynasty (1046–256). The New Year,...