Chinese Consul-General in Chicago Zhao Jian speaks during the opening ceremony of the photo exhibition "The Chinese and the Iron Road -- Building of the Transcontinental" in Chicago, the United States, on May 24, 2019. A photo exhibition in memory of Chinese migrant workers' contribution to U.S. Transcontinental Railroad 150 years ago kicked off Friday at Thompson Center in Chicago. The exhibition, "The Chinese and the Iron Road -- Building of the Transcontinental", will last for seven days at the state-owned building. (Xinhua/Wang Ping)