The President's Lady: A Novel about Rachel and Andrew Jackson; by Irving Stone.

In this Stone takes up the era of exploration of the land and large part of continent that is now USA, and the story of a good woman and a good man who were maligned due to the then conventions for no fault of their own - the fault in fact lay with the man who had lied and allowed them to believe that there had been a divorce, while he had simply not done it. Much life threatening dangers were braved by the explorers, which is difficult in this era of mobile (cell) phones and GPS and so on to imagine.