SALT LAKE CITY - Pioneer Day is the biggest annual celebration of America's westward expansion.
It's also called the Days of '47.
But in the days of '46, an almost equally famous group of pioneers traveled through the Salt Lake Valley.
Half of them died within months because of the route they chose, and the survivors cursed the man who convinced them to travel through Utah.
The video above describes the role of Utah, and a man named Lansford Hastings, in one of the darkest chapters in the history of the American West.