Lewis and Clark National Historic Trail

By editor

Big Sandy, Chouteau County, Montana

The Lewis and Clark National Historic Trail threads its way through the Missouri River corridor near Big Sandy, Montana, tracing the footsteps of the Corps of Discovery as they pressed westward between 1804 and 1806. This particular section, crossing the high plains of north-central Montana, offers a landscape that has endured with remarkable fidelity to its early 19th-century condition. The broad expanse of grassland, punctuated by rugged coulees and ancient river terraces, reveals layers of deep time beneath the surface, while the Missouri River winds like a silver ribbon, still shaping the land as it did two centuries ago.

The journey through this stretch was among the most grueling of the entire expedition. From the confluence with the Marias River to the Great Falls, the Missouri River transforms from a majestic artery into an obstinate, shallow stream riddled with sandbars and sudden bends. The swift current and treacherous bars forced the men to abandon easy navigation, compelling them to wade through frigid waters to haul their canoes upstream. The riverbanks are carved by steep coulees -- narrow ravines formed by millennia of erosion -- which interrupt the otherwise flat plains. These geological scars hint at the cataclysmic floods and slow geological uplift that shaped the region long before human eyes witnessed it.

The plains themselves are a study in ecological resilience. Prickly pear cactus (Opuntia polyacantha), with its flat, spiny pads, carpets the dry uplands. These plants, adapted to the semi-arid climate and thin soils, inflicted painful wounds on the explorers’ moccasins and bare feet. Meriwether Lewis recorded the challenge with stark clarity: the men’s feet were “limping from the soreness” caused by the relentless abrasion. Patrick Gass, the expedition’s carpenter and chronicler, described the ordeal on June 1, 1805, writing, “The river is very crooked and full of sand bars. The men are obliged to wade and haul the canoes over the shoals, which is very hard and fatiguing labour.” The physical strain of this passage tested the endurance of even the most seasoned members of the Corps.

The Missouri River itself is a geological marvel. Flowing from the Rocky Mountains in southwestern Montana, the river here meanders across a broad alluvial plain formed during the Quaternary period, roughly 2.6 million years ago to the present. The river’s shifting channels have left terraces that rise in steps above the modern floodplain, each representing a former river level altered by climatic changes and sediment deposition. The presence of these terraces allowed the expedition to find dry ground for their camps amid the challenging terrain. Yet the constant threat of sudden flooding remained, a reminder of the river’s restless nature.

To the south, the Bears Paw Mountains rise abruptly from the plains, their volcanic origins dating to the Eocene epoch, about 50 million years ago. This range, composed largely of basaltic lava flows and breccias, forms a dark silhouette against the sky. The Bears Paw present a stark contrast to the rolling grasslands, an island of stone where hardy junipers (Juniperus scopulorum) and ponderosa pines (Pinus ponderosa) cling to rocky slopes. The mountains later became a crucible of human history when the Nez Perce tribe, fleeing U.S. Army forces in 1877, made their final stand near these same hills. Chief Joseph’s poignant surrender at Bear Paw Mountain, just 40 miles from the Canadian border, marked the end of their arduous flight.

The flora along the trail reflects the transition between riverine and upland ecosystems. Cottonwoods (Populus deltoides) line the riverbanks, their broad leaves rustling in the steady wind. Beneath these giants, chokecherry bushes (Prunus virginiana) and wild rose (Rosa woodsii) provide shelter and food for local fauna. The grasslands, dominated by bluebunch wheatgrass (Pseudoroegneria spicata) and needle-and-thread grass (Hesperostipa comata), support species such as pronghorn antelope (Antilocapra americana) and the elusive swift fox (Vulpes velox), both observed by the expedition.

The expedition’s journals reveal acute observations of this environment. William Clark, noting the physical toll of the cactus, remarked on the men’s “limping from the soreness of their feet.” This practical note captures the intimate and often harsh engagement between humans and the land. Lewis and Clark’s scientific curiosity extended beyond survival; they cataloged plants, animals, and geological phenomena with the precision of natural historians, laying groundwork for future studies.

Their passage through this region occurred during late spring and early summer of 1805, a time when the Missouri’s water levels were influenced by snowmelt from the mountains. The cold river water penetrated the men’s clothing and skin, compounding their fatigue. The experience of hauling canoes upstream, wading through swift currents while balancing on slippery rocks, must have demanded every ounce of strength and determination.

One can still sense the physical landscape that shaped their journey. The shallow, braided channels of the Missouri here contrast with the deep, narrow gorge they would encounter further downstream near Great Falls, where the river plunges through a series of waterfalls and cataracts. That section required them to carry their boats and supplies overland for nearly 18 miles -- a monumental effort that would test their resolve anew.

The Lewis and Clark National Historic Trail, maintained by the Department of the Interior and the Bureau of Land Management, preserves these segments of the journey. Visitors walking along the riverbanks near Big Sandy today encounter many of the same grasses, shrubs, and geological formations that greeted the Corps of Discovery. The landscape’s quiet endurance offers a direct link to the past and invites reflection on the complexities of exploration, survival, and the interplay of natural forces.

In tracing this path, one gains a deeper appreciation for the arduous endeavor undertaken by Lewis, Clark, and their men. Their records not only chronicled a route across the continent but provided detailed scientific observations that enriched the understanding of North America’s western lands.

As William Clark expressed in his journal, the river’s challenges were formidable: "The river is crooked and full of sand bars, which makes navigation extremely difficult and laborious." This simple statement encapsulates the persistent obstacles posed by the natural world, challenges that tested the limits of human endurance and ingenuity.

Through this stretch of Montana, the Lewis and Clark National Historic Trail conveys a narrative of geological forces sculpting land and water, of ecosystems adapted to climatic extremes, and of men confronting nature’s demands with resilience and curiosity. The Missouri River, the prairie, and the ancient volcanic Bears Paw Mountains together form a landscape both timeless and dynamic, bearing silent witness to one of America’s greatest explorations.

See also

• Lewis and Clark National Historic Trail at Big Sandy, Chouteau County
• Lewis and Clark National Historic Trail at Loma, Chouteau County
• [An Island on the Plains](/