The human cost of building railways.
A way of travelling across the USA from coast to coast, especially after the Donner group, was urgently needed. The Chinese immigrants brought in for the gold mining were subjected to much racial discrimination and forcibly removed from mining claims regardless of any legitimate land ownership and so they were looking for new jobs. Charles Crocker, construction chief of the Central Pacific Rail Road needed a workforce to push the CPRR tracks towards Utah. He ended up with a workforce of about 12,000 Chinese workers. A railway retaining wall, the China Wall of Sierra stands a a monument to these master Asian builders. The Donner Pass snow sheds, long abandoned were buit between 1866 and 1868 by Chinese workers who laboured under treacherous conditions. Explosives, hand chisels and wheelbarrows formed the toolkit of those workers. Nobody knows how many died or were injured because nobody cared; estimates are about 1,200.
Inside the tunnels; these days the tunnels are known as the graffiti tunnels.