http://www.goodreads.com/book/show/6895978-a-country-of-vast-designs
Excellent reading for a period of American history that is rarely studied.
James K. Polk committed himself to being the most consequential single term US President 1845-1849 by adding Texas, California and Oregon territories; reestablishing an independent Treasury and reducing tariffs. The territorial expansion fulfilled the national “Manifest Destiny”…the goal of being a nation from Atlantic to the Pacific Oceans (sea to shining sea).
Polk was an unlikely candidate having lost two races for Governor of Tennessee. (However, he had been the Speaker of the House for Andrew Jackson and a one term Tennessee governor.) He won the Democratic nomination on the sixth ballot!
James K. Polk accomplished great things in an era when letters were delivered by horseback. Railroads were a novelty. Newspapers were the media for the masses. Imagine! The author Robert W. Merry brought authenticity with many quotes from Polk’s diary, congressional records and newspapers of the day.
elfcroft 
Very good. I like history from that time period.