Passengers show Spring Festival couplets and a piece of calligraphy of Chinese character "Blessing" at the railway station in Lanzhou, capital of northwest China's Gansu Province, Jan. 21, 2017. China's annual Spring Festival travel rush, "Chunyun," is regarded as the largest human migration on earth. Trains have witnessed the migration every year. About 2.98 billion trips are expected to be made during "chunyun" this year that lasts from Jan. 13 to Feb. 21, up slightly from a year ago. Spring Festival, or the Chinese lunar new year, is the most important occasion for family reunions in China. (Xinhua/Chen Bin)