U.S. Secretary of Transportation Elaine L. Chao delivers a speech during the celebration for the 150th anniversary of the completion of the nation's first transcontinental railroad, to which thousands of Chinese railroad workers have made great contribution, at the Golden Spike National Historical Park at Promontory Summit, an area of high ground roughly 100 km northwest of Salt Lake City, the United States, May 10, 2019. (Xinhua/Li Ying)