The main pass, Donner Pass, is named for one of the parties of 1846. A combination of bad decisions and poor luck delayed the party's arrival to the pass until October 31. There followed early snowfalls.

Accustomed to weather in the east, the party went back to Donner Lake hoping the snow would melt. In the high Sierra, even an early snow does not melt. The snow piled higher and higher, the oxen were covered and lost, and life became unendurable. On December 15, a portion of the Donner Party, called the Forlorn Hope, headed out on snowshoes for California to get help.

They crossed Donner Summit where, shortly thereafter, the members of the group began dying. By the time they reached California they were cold, starved of food and, with all hope seemingly lost, turned to cannibalism as a last resort.

The surviving members of Forlorn Hope, five women and two men, stumbled into California. Rescue missions were started, and some of the most heroic and terrible examples of human nature followed as half of the Donner Party was rescued over Donner Summit. Of the original Donner Party, half had starved to death.