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.