The romantic image of pioneers riding in covered wagons across the plains is almost entirely fiction. Prairie schooners had no springs and were built for cargo, so nearly every man, woman and child walked the roughly 2,000-mile Oregon Trail on foot, covering close to a marathon a day for months. This episode strips away the video game and Hollywood myths to look at the diaries and historical data behind why more than 400,000 people chose this brutal journey between 1840 and 1869.

The story begins with fur trader Robert Stewart stumbling onto Wyoming's South Pass in 1812, a route that sat unused for decades until the collapse of the beaver-pelt hat market left skilled mountain men unemployed and looking for work as guides. From there the conversation covers the mule-versus-ox debate, the ordeal of shoeing an ox, the graveyard of abandoned fu ...