While significantly longer, the Feather River Route was preferred by some over the Donner Pass route (elevation about 7,000ft[2,100m]) over the Sierra Nevada mountains, because the former's summit under Beckwourth Pass is at a lower elevation (about 5,000ft[1,500m]) and most of the route follows a gentler grade along the Feather River.
↑Hoover (2002). Historic spots in California (Fifthed.). Stanford University Press. ISBN9780804778176. The Western Pacific line between Oroville and Chilcoot has thirty-four tunnels. ... Spring Garden is 7,344 feet in length and the Chilcoot tunnel is 6,002 feet.