Key collection tells tale of progress

After starting his career during the era of steam locomotives, Sun Mingjin looks forward to touring country by bullet train

Train attendant Sun Mingjin is working through his 39th Spring Festival travel rush, which began on Jan 21 and will not officially end until March 1.

Known in China as chunyun, the period in which people traditionally return to their hometowns to celebrate the Lunar New Year, the travel rush has become known as the world's largest annual human migration.