[1] It is owned by the Union Pacific Railroad,[2] in service as a part of the Roseville Subdivision of the Overland Route.
Daily freight trains as well as Amtrak's California Zephyr utilize the line.
The first bore through the Sierras, Tunnel Number 6, was built as part of the first transcontinental railroad.
In 1901, Southern Pacific Company proposed building a long tunnel via a new alignment to both lower the track elevation and cut several miles off of the Donner Pass route.
The uncertain corporate fate of the Central Pacific Railroad and the outbreak of World War I stalled further work.