"[This] richly documented book is the definitive study of the decisive role mountain men played in the exploration and expansion of the Western frontier." —Jay P. Dolan, The New York Times Book Review Early in the nineteenth century, the mountain men emerged as a small but distinctive group whose knowledge and experience of the trans-Mississippi West extended the national consciousness to continental dimensions. Though Lewis and Clark blazed a narrow corridor of geographical reality, the West remained largely terra incognita until trappers and traders—such as Jim Bridger, Kit Carson, Tom Fitzpatrick, and Jedediah Smith—opened paths through the snow-choked mountain wilderness. These and other Mountain Men opened the way west to Fremont and played a major role in the pivotal years of 1845–1848 when Texas was annexed, the Oregon question was decided, and the Mexican War ended with the Southwest and California in American hands—thus making the Pacific Ocean America's western boundary.