A party of 15 snowshoers that attempted to make its way through the snow-choked passes in December to get help suffered horribly; about half of them survived to get aid from Sutter's Fort. Many of the emigrants died during the winter. Some surviving members of the Donner Party were reputedly driven to cannibalism, but despite archaeological examinations of the remains, cannibalism has never been definitively proved. Finally, expeditions from the Sacramento valley made their way through the snowdrifts to rescue the hunger-maddened migrants. Only about half of the original party of 81 reached California. The survivors later disagreed violently as to the details of (and particularly the blame for) the disaster. Donner Lake, named for the party, is today a popular mountain resort near Truckee. The large bronze Pioneer Monument (1918) erected at the lake is dedicated to the party. Nearby Donner Pass has a U.S. weather observatory.
See C. F. McGlashan, History of the Donner Party (1879, repr. 1966); G. R. Stewart, Ordeal by Hunger (1936, new ed. 1960); E. Rarick, Desperate Passage (2008).
On May 19, 1846, the Donners and Reeds joined a large wagon train captained by William H. Russell. Most of those who became members of the Donner Party were also in this group. For the next two months the travelers followed the California Trail until they reached the Little Sandy River, in what is now Wyoming, where they camped alongside several other overland parties. There, those emigrants who had decided to take a new route ("Hastings Cutoff", named after its promoter, Lansford Hastings), formed a new wagon train. They elected George Donner their captain, creating the Donner Party, on July 19. At its height it numbered 87 people.
The Donner Party continued westward to Fort Bridger, where Hastings Cutoff began, and set out on the new route on August 31. They endured great hardships while crossing the Wasatch Mountains and the Great Salt Lake Desert, finally rejoining the California Trail near modern Elko, Nevada, on September 26. The "shortcut" had taken them three weeks longer than the customary route. They met further setbacks and delays while traveling along Nevada's Humboldt River.
When they reached the Sierra Nevada at the end of October, a snowstorm blocked their way over what is now known as Donner Pass. Demoralized and low on supplies, about three quarters of the emigrants camped at a lake (now called Donner Lake), while the Donner families and a few others camped about six miles (ten kilometers) away, at Alder Creek.
The emigrants slaughtered their remaining oxen, but there was not enough meat to feed so many for long. In mid-December, fifteen of the trapped emigrants, later known as the Forlorn Hope, set out on crudely fashioned snowshoes for Sutter's Fort, about 100 miles (160 kilometers) away, to seek help. This group consisted of 10 men and five women. When one man gave out and had to be left behind, the others continued, but soon became lost and ran out of food. Caught without shelter in a raging blizzard, four of the party died. The survivors resorted to cannibalism, then continued on their journey; three more died and were also cannibalized. Close to death, the seven surviving snowshoers—two men and all five of the women—finally reached safety on the western side of the mountains on January 18, 1847.
Californians rallied to save the Donner Party and equipped a total of four rescue parties, or "reliefs". When the First Relief arrived, 14 emigrants had died at the camps and the rest were extremely weak. Most had been surviving on boiled ox hide, but there had been no cannibalism. The First Relief set out with 21 refugees on February 22.
When the Second Relief arrived a week later, they found that there had been no more deaths, but some of the 31 emigrants left behind at the camps had begun to eat the dead. The Second Relief took 17 emigrants with them, leaving 14 alive at the camps. When the Third Relief arrived later in March, they found nine left. They rescued four children, but had to leave five people behind. By the time the Fourth Relief reached the camps on April 17, they found only one man alive. Louis Keseberg, the last member of the Donner Party, arrived at Sutter's Fort on April 29.
Of the original 87 pioneers, 39 died and 48 survived. Five died before reaching the Sierra Nevada, 14 at the lake camp, 8 at Alder Creek, and 12 while trying to escape the mountains. Two California Indians who helped bring supplies from Sutters Fort were trapped along with the emigrants and also died, bringing the total to 41 deaths.