The Donner Party was made of a group of 90 emigrants, and led by Jacob and George Donner. They wanted to take a new, shorter route to California, but eventually became trapped in the Sierra Nevada Mountains.
They decided to take an "easier" trail that was laid out by a trail guide named Lansford Hasting, but he was not at Fort Bridger, he left note that he was going to mark the trail for them.
They were following the trail, but it was more difficult than they thought. They sent a messenger, and after 8 days he returned with a message from Hastings to follow another trail. The emigrants had to carve a fresh road through thick trees.
On October 28, a heavy snowfall blocked the high mountain passes, trapping the emigrants. Eventually reduced to cannibalism to survive, only 45 of the original 89 emigrants reached California the following year.
The Donner Party finally made their way through the Wasatch Mountains and arrived at the Great Salt Lake.