The Oregon Trail by Francis Parkman, Jr.

Classic work of history. According to Wikipedia: Francis Parkman (September 16, 1823 - November 8, 1893) was an American historian, best known as author of The Oregon Trail: Sketches of Prairie and Rocky-Mountain Life and his monumental seven volume France and England in North America. These works are still valued as history and especially as literature, although the biases of his work have met with criticism.