Book excerpt: 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--Jim Bridger, Kit Carson, Tom Fitzpatrick, Jedediah Smith--opened paths through the snow-choked mountain wilderness. They 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, the Pacific Ocean becoming our western boundary.