Lost States: True Stories of Texlahoma, Transylvania, and Other States that Never Made it.  An amusing collection of forgotten statehood proposals 

Fun Maps
A delightful little collection of map curiosities. 

Fantastic Facts about the Oregon Trail 
Amazing true tidbits about the pioneers who ventured west on the Oregon Trail.

Across the Plains in 1844 
Annotated edition of Catherine Sager's influential diary.