Children pose for a group photo at Nanjing South Railway Station in Nanjing, east China's Jiangsu Province, Jan. 10, 2020. China, the world's most populated country, on Friday ushered in its largest annual migration, 15 days ahead of the Spring Festival, or the Lunar New Year. There will be three billion trips during the travel rush from Jan. 10 to Feb. 18 for family reunions and travel, slightly up from that of last year, according to a forecast from the National Development and Reform Commission (NDRC). (Xinhua/Ji Chunpeng)