In 1804, John Colter set out with Meriwether Lewis and William Clark on the first US expedition to traverse the North American continent. During the 28- month ordeal, Colter served as a hunter and scout, and honed his survival skills on the western frontier. But when the journey was over, Colter stayed behind. He spent two more years trekking alone through dangerous and unfamiliar territory, charting some of the West's most treasured landmarks. Historian...