A section of track on the Humboldt Plains stretches into the distance at the same site as it did 150 years ago. Li identified all the sites captured in more than 360 photographs taken by Hart during the 1860s. [Photo provided to China Daily]

At Cape Horn, a 5-km roadbed curving along steep slopes some 400 meters above the American River east of Colfax, Chinese workers were lowered down the cliffs in baskets to plant explosive charges.

In winter, fierce blizzards would often block tunnel entrances and trigger avalanches that swept away the worker's camps-carrying many of them to their deaths, according to the Stanford project.

It's estimated that nearly 1,200 Chinese railroad workers died from work-related accidents, avalanches and explosions while toiling through the Sierra Nevada.

In honor of the Chinese workers and their sacrifices, the California Assembly passed a resolution last year to designate May 10 as California Chinese Railroad Workers Memorial Day.

"As a fourth-generation Chinese American, I think it is very important for all Americans to commemorate the historical significance of the experiences of Chinese railroad workers," says Evan Low, California Assembly member and author of the resolution.

He says the resolution was an important step not only to address racism in American history and society, but also to emphasize the railroad workers' contribution to the country's economy in general and the development of Silicon Valley.

Next year marks the 150th anniversary of the completion of the First Transcontinental Railroad. Many celebrations have been planned to mark the occasion, including a commemorative ceremony at the Chinese American Memorial Museum in San Jose History Park.

The Stanford project also has received several requests to host photo exhibitions across the US to commemorate the 150th anniversary, according to Li.

He has produced four sets of panels to be exhibited, each containing around 100 photos, with the help of the project and Chinese volunteers.

"More and more people in China are taking an interest in the history of the Chinese railroad workers. The 150th anniversary will be a great opportunity to promote the history and the friendship between the two countries dating back as far as 150 years ago," says Li.