Ever since Lewis and Clark set out to determine what the US actually acquired from the Louisiana Purchase (1803), Americans dreamed of ways to expand and connect the eastern and western regions of the country. Development of the railroads and the creation of rail networks during the 1830s and 1840s shortened travel and promoted rapid commercial development east of the Mississippi. Further acquisitions of Texas and other formerly Mexican territory on the west coast spurred interest in the 1840s to build a continuous rail line extending to the west coast. Perhaps such a railroad could help to diminish the sectionalism that was threatening the stability of the Nation. However, the 1850s saw sectionalism grow ever stronger as the debates over slavery intensified. Nonetheless, in 1862, after the Civil War had begun, President Abraham Lincoln signed the Pacific Railway Act that set in motion the plan for building the first transcontinental railroad: Two Companies, the Central Pacific starting in Sacramento, California, and the Union Pacific, starting on the Iowa-Nebraska border, would work towards each other.

Work on the railroad was sporadic until the end of the Civil War. Then efforts increased rapidly and the need for labor became intense. Charles Crocker, one of the “Big Four” railroad developers who co-founded the Central Pacific Railroad, at first opposed suggestions of hiring Chinese workers, but became convinced that, indeed, a plan to bring Chinese workers over from China could prove beneficial – after all, hadn’t the Chinese built a great wall? In 1865 about 4,000 Chinese were employed on the railroad; in 1868, it is estimated as many as 12,000 were working at one time. Overall, perhaps as many as 20,000 Chinese workers helped build the TCRR over the duration of its construction.

In 2021, the Donner Summit Tunnel was designated by the Department of the Interior and the National Park Service as being in danger of being lost, the first step towards recognition of the tunnels as a national historic landmark (nil). Historic and archaeological work is ongoing to further that goal.