The Forty-Niners, A Chronicle of the California Trail and El Dorado by Stewart Edward White

Classic western. According to Wikipedia: Stewart Edward White (12 March 1873 – September 18, 1946) was an American author. Born in Grand Rapids, Michigan he earned degrees from University of Michigan (Ph.D., 1895; M.A., 1903). From about 1900 until about 1922, he wrote adventure travel books.