The Donner Party was made up of eighty-seven migrants in 23 wagons heading to the modern-day American state of California from Sangamon County, Illinois. The Donner Party actually consisted of two families: the Donners and the Reeds.
They left Illinois in 1846 and had much difficulty passing the Great Salt Lake in the modern-day state of Utah. By November they were trapped by heavy snow in the Sierra Nevada Mountains and were forced into camping at a small lake (now called Donner Lake).
Reports seem to vary, but a party of perhaps sixteen or twenty-eight attempted a crossing of the Sierra Nevada mountains. Ultimately this party landed in deep, impassable snow, their supplies running low and they were reported to have resorted to cannibalism in order to survive the winter. Reportedly nine men died and seven were eaten by hungry companions. Seven (five women, two men) reached safety over the mountains in February, 1847, naked and frostbitten.
In 2003 near the modern city of Truckee, California by Lake Tahoe, close by Alder Creek archeologists found a campfire pit and solid evidence that cannibalism actually took place; a bone fragment of a "large mammal" bearing butcher marks of an ax was discovered; at present writing (August 20, 2003) it has not been verified as human (someone please fill this in if more information comes available).
Eventually forty-seven of the group were rescued and brought to California over what is now called Donner Pass.