U.S. Secretary of Transportation Elaine Chao speaks ahead of a three-day celebration set to kick off on Friday, for the 150th anniversary of the transcontinental railroad's historic completion, in Salt Lake City, the United States, May 9, 2019. Chao here on Thursday commemorated thousands of early Chinese workers who helped build the first transcontinental railroad in the United States, prior to the 150th anniversary of its completion. (Xinhua/Li Ying)

U.S. Secretary of Transportation Elaine Chao speaks ahead of a three-day celebration set to kick off on Friday, for the 150th anniversary of the transcontinental railroad's historic completion, in Salt Lake City, the United States, May 9, 2019. Chao here on Thursday commemorated thousands of early Chinese workers who helped build the first transcontinental railroad in the United States, prior to the 150th anniversary of its completion. (Xinhua/Li Ying)