If you're looking for
one book that will explain the political causes of the American Revolution, you can't go wrong by going to a good used book dealer and digging up a copy of
Origins of the American Revolution by John C. Miller.
Published in 1943 by Little, Brown and Company, it is pre-PC and an excellent read.
MASSACRES OF THE MOUNTAINS by J. P. Dunn Jr
A definite iconclastic view of the Indian wars---If you can find a copy.
Written around 1888, you will learn things never taught in modern histories.
Chapters on Sand Creek and The Washita battles deserve special mention.