The Plains Across: the overland emigrants and the trans-Mississippi West, 1840-60 John D. Unruh, Jr 
One of three finalists of the Pulitzer Prize in history and winner of seven awards including the John H. Dunning Prize of the American Historical Association and National Historical Society Book Prize. " A tour de force ....The most penetrating and comprehensive study of the epic Oregon-California migrations to date, and the finest kind of a published, or hear the wide acclaim which has greeted his achievement.