Mountain Passes
Two mountain chains traverse America from north to south, the Appalachians and Rockies, and both formed barriers to westward movement. Early hunters in search of pelts and pioneers who coveted western lands met the difficulty by finding natural outlets through the mountains. Early trails were, when possible, water trails, so the Mohawk and the Ohio Rivers were the key routes to the Great Lakes and the Mississippi Valley. The Iroquois and French barred the Mohawk route on the north, and the Cherokees and other confederate tribes blocked routes through the lowlands south of the Appalachians. Accordingly, the confluence of the Allegheny and Monongahela Rivers at Pittsburgh and the breaks in the mountain ridges in the corner between Virginia and North Carolina leading into Kentucky were the points of easiest passage. Such gaps in the Appalachians were frequently the result of troughs cut through the mountain slopes by rivers seeking an outlet to the Ohio or the Atlantic Ocean. The Virginia coast range is low, but early maps show only three passes into the Shenandoah Valley: Williams, Ashby, and Vestal Gaps, all in Fairfax County.
The most important pass in the Kentucky approach was the Cumberland Gap, which led by way of the Holston and Clinch Rivers in eastern Tennessee over and through the mountains and then along the Kentucky River and its tributaries to the Falls of the Ohio. This was known as Boone's Wilderness Road. Early travelers also noted Flower Gap, from tidewater to the sources of Little River; Blue Ridge Gap, another passage from tidewater to the Shenandoah Valley; and Moccasin Gap, between the north fork of the Holston and Clinch Rivers.
Those headed west encountered Chester's Gap in the Blue Ridge Mountains on the Virginia road by Braddock's Road to Pittsburgh. They crossed Miller's Run Gap on the Forbes Road, running west from Philadelphia to Pittsburgh, northwest of the present site of Ligonier, in Westmoreland County, Pa.
The Rockies, because of their uninterrupted length and great height, offered a more serious problem. For the most part, early Spanish missionaries at the south and fur traders, emigrants, and army explorers at the north and center unlocked their secrets. Spaniards made the earliest approaches in the south when pushing into California from New Mexico. After Mexico revolted and American trade with Santa Fe began, fur trappers thrust westward from Taos and Santa Fe to San Diego and Los Angeles. The river valleys unlocking the southern route to the West were the Gila and the Colorado. The Colorado trail, known as the Spanish Trail, went north from Taos, crossed the Wasatch Mountains and Mojave Desert, and entered California by the Cajon Pass. The Gila route was the shorter trail from Santa Fe, going west across the mountains and, by way of Warner's Pass, eventually reaching San Diego.
By following the Arkansas River west to Pueblo, Colo., and crossing the mountains by a choice of three or four different passes, the Williams or Sandy Hill, the Roubideau or Mosca, and the Sangre de Cristo or Music Passes, travelers could reach Taos by turning south or California by turning northwest on a route traced by John C. Frémont. This route crossed the Great Basin of Utah and Nevada and surmounted the Sierra Nevada passes in California. The most important of these passes were the Walker, the Carson, the Virginia, the Frémont, the Sonora, the Donner, and the Truckee. After travelers had scaled the eastern escarpment, there still remained mountain folds in the Sierra Nevada that impeded progress to the coast. The Tehachapi Pass into San Joaquin Valley crossed one such fold.
The central approach to the Rockies was by way of the Platte River, which sends fingers high up into the mountains. The most important pass in the entire Rocky Mountain chain, South Pass, was on this route. It has easy grades, and many travelers bound for California used it by turning south at Fort Hall, Idaho.
Of all river approaches, the Missouri was the most effective and was the route that Meriwether Lewis and William Clark used. They crossed the Rockies by Lemhi, Clark, and Gibbon Passes. Other useful passes of the Northwest were the Nez Perce and Lo Lo through the Bitterroot Mountains on the Montana and Idaho border. The Bozeman Pass offered access from the valley of the Gallatin River to that of the Yellowstone River. For traveling south from Oregon to California the Siskiyou Pass proved useful.
Important passes in the midcontinental region were the Union, crossing the Wind River Mountains in southwestern Wyoming; Cochetope Pass over the San Juan Mountains in southwestern Colorado, used by Frémont and others in passing from Colorado to Utah; and Muddy Pass, two degrees south of South Pass, which was useful in crossing the Atlantic and Pacific divides from Platte headwaters. Bridger's Pass, discovered in the early days of the fur trade, crossed the divide south of South Pass and saved distance on the California route; for this reason, it was used by the Pony Express.
Bibliography
Carnes, Mark C., and John A. Garraty et al. Mapping America's Past: A Historical Atlas. New York: Henry Holt, 1996.
Earle, Carville. Geographical Inquiry and American Historical Problems. Stanford, Calif.: Stanford University Press, 1992.
Meinig, D. W. The Shaping of America: A Geographical Perspective on 500 Years of History. New Haven, Conn.: Yale University Press, 1986.
Nevins, Allan. Frémont: Pathmarker of the West. Lincoln: University of Nebraska Press, 1992.
