South Pass: The 20-Mile Gap in the Rockies That Opened the Western Trails

The Rocky Mountains stretch like a jagged spine between Alaska and Mexico, splitting North America into East and West. The Continental Divide is not a single line of peaks but a complex of overlapping ranges and treeless sagebrush steppe, hundreds of miles wide, and for covered-wagon travelers it was a barrier to people, commerce and communications. The National Park Service tells how one 20-mile-wide gap in Wyoming, South Pass, changed that.

"Emigrants Crossing the Rocky Mountains." Image courtesy of the Library of Congress.

A secret the tribes already knew

Early explorers looked in the Northern Rockies for a fabled Northwest Passage. Lewis and Clark's Corps of Discovery ended that hope in 1805, when it nearly perished crossing the Bitterroot Range at Lemhi Pass in Montana. But the Absarokas (Crows), Shoshones and other tribes knew an easier gateway some 400 miles farther south, in what is now Wyoming.

Fur traders of the Pacific Fur Company found it in 1812. Robert Stuart and his men left Fort Astoria on the Columbia River in June to carry business dispatches overland to New York. A Shoshone guide, before leaving them, told them of a shorter route through the central Rockies. Three months in, an Absaroka war party took all their horses near the Teton Range, leaving them on foot, a thousand miles from any settlement with winter coming. They followed an Indian trace south of the Wind River Range and through a broad pass over the Great Divide, spent a hungry winter on the plains of eastern Wyoming and reached St. Louis in April 1813 with news of the pass.

Forgotten, then found

The news was drowned out by the War of 1812. The pass was forgotten until friendly Absarokas guided a small party of mountain men, among them Jedediah Smith, James Clyman and Thomas Fitzpatrick, through it in 1824.

Then the pass went to work. Trappers and pack-mule caravans carried supplies over South Pass to the annual fur-trade Rendezvous. William Sublette took the first wagons to Rendezvous in 1830 but stopped just east of the Divide, and went back to pack mules the next year. Captain Benjamin L. E. Bonneville blazed the first wagon track over South Pass in 1832 with a 20-wagon supply train. Missionaries Marcus and Narcissa Whitman and Henry and Eliza Spalding crossed with the fur brigade in 1836, showing that women could take the trail. In 1840, Joel and Mary Walker, with four children and two covered wagons, joined the last supply caravan to the last Rendezvous and reached Oregon in September; their example, and the birth of a daughter that January, showed that mothers and children could make the 2,000-mile trip and helped open the floodgates of emigration.

The gateway

South Pass, the Gateway to the West. Photo: NPS.

Over the next three decades, government survey parties and soldiers, missionaries, wagon and handcart companies, gold-seekers, stage and mail coaches, freight wagons, Pony Express riders and the transcontinental telegraph all funneled through the 20-mile-wide passage. The ground is still scored with ruts. Without South Pass, the NPS says, there would have been no Oregon Trail, no California Trail, no Mormon Utah, and perhaps no United States stretching from the Atlantic to the Pacific.

Sources

• National Park Service, "Gateway to the West: National Historic Trails Across the Continental Divide" (https://www.nps.gov/articles/000/gateway-to-the-west-national-historic-trails-across-the-continental-divide.htm), adapted from the National Historic Trails Auto Tour Route Interpretive Guide: Across Wyoming; rewritten in hubnx's own words.