The world’s largest human migration, China’s Spring Festival travel rush, can be traced back more than 2,000 years. This year’s travel rush, called chunyun, runs from February 2 to March 13 and is expected to create 9.5 billion passenger trips. The tradition began during the Zhou dynasty (1046–256 BC) with the term guo nian, meaning spending the New Year. Back then, the New Year was celebrated with rituals to pray for a good harvest. It also started the custom of family reunions to honor Confucian values of filial piety. Early New Year journeys were long and difficult, taking up to a month by land and sea, mainly for the rich and powerful. Over centuries, China’s transport systems developed, making the massive modern travel rush possible.