This American Life contributor Sarah Vowell tells the story of a mapmaker named Charles Preuss who charted the Western Territories with two of American history's legendary explorers—John Charles Fremont and Kit Carson. The maps Preuss made were best sellers and helped open the Western frontier to settlement.

Sarah Vowell examines what happens when TV takes on a subject it really has no business exploring at all, but seems fairly obsessed with nonetheless: The Pilgrims. Sarah's most recent book is Assassination Vacation.