In the wake of the Lewis and Clark expedition a succession of explorers, mainly U.S. army officers, surveyed and mapped large tracts of the Louisiana Purchase, the Rockies and the Pacific coast. The earliest was Zebulon M. Pike, whose first expedition (1805) failed to discover the source of the Mississippi, but whose second (1806-1807) took him to Colorado and to the headwaters of the Arkansas and Red rivers and across the closed border of the Spanish Southwest. Pike’s account of his travels did much to popularize the myth of the Plains as the “Great American Desert,” an impression confirmed by explorer Stephen H. Long after his expedition to the Rockies in 1820. But by the 1840s, a new sentiment had taken hold — that it was America’s “manifest destiny” to expand across the continent. The spirit of expansionism was fueled by the efforts of John C. Fremont who, guided by mountain-man Kit Carson, led expeditions to the Rockies (1842); over the Oregon Trail (1844); and into California (1845-1846), where he joined American settlers in the Bear Flag revolt against Mexican rule. Though Fremont discovered no new routes, and thus did not technically merit the nickname the “Pathfinder,” he gathered important geographical data and ignited popular interest in western settlement with his glowing reports.

A unique breed of tough, self-reliant loners, the trappers and pioneers who called themselves “mountain men” became in the 1820s and 1830s the trail blazers of the Far West. Chafing at the restraints of settled society and attracted by the West’s profusion of wildlife, they went in search of beaver pelts and other furs, some as members of the fur companies but many independently. They learned Indian languages and customs, often married Indian women, and generally came to resemble Native Americans in dress, eating habits and fighting methods. Spending most of their time in the wild, mountain men gathered each summer at a prearranged spot for the annual rendezvous. There, joined by traders, fur company representatives, and Indians, they traded, drank, gambled and caroused in a raucous celebration.

Several mountain men won fame as explorers. Thus James Bridger (1804-1881) became the first white to visit the Great Salt Lake (1824); Jedediah S. Smith (1798-1831) rediscovered the South Pass (1823-1824), and later led a party through the Great Basin and Mojave Desert into California (1826); Kit Carson (1809-1868) blazed trails in the province of New Mexico (1826-1831); and Joseph Reddeford Walker journeyed from the Rockies to the Pacific, camping near Yosemite Valley in 1833.