Passengers strand at Shanghai's Hongqiao Railway Station Monday night. A train on the Shanghai-Hangzhou route broke down due to rain and snow, affecting more than 30,000 passengers in Hongqiao Railway Station alone. China's largest annual migration, with tens of millions of people heading home for the lunar new year holiday, started on January 24 and will last for 40 days. See our reports inside for additional insight into this annual social phenomenon. Photo: IC