The Impassable Barrier:

Captain Jones and the 1873 March That Opened Yellowstone’s Back Door to Montana

A Territory Still Being Invented

In the summer of 1873, the map of northwestern Wyoming and southern Montana remained, in large part, a rumor. Yellowstone had been withdrawn from settlement as the nation’s first national park only the year before, in March 1872, but withdrawal on paper was not the same as knowledge on the ground. Army engineers, geologists, and a handful of civilian boosters understood that the new park sat inside a knot of mountains that no one had adequately surveyed, and that the routes connecting it to the mining camps and rail lines of Montana Territory existed mostly as guesswork and Indian trail. It was into this uncharted territory that Captain William A. Jones of the Army Corps of Engineers rode that June, at the head of a modest column bound for a stretch of country so rugged that his own report would later credit him as the first military engineer to survey and map it (National Park Service).

Jones was not a newcomer to frontier survey work. He had served in the Civil War, taught engineering at West Point, and worked as engineer of the Department of the Platte, where he witnessed the joining of the Union Pacific line in 1869 and had already led a reconnaissance into Utah’s Uinta Mountains in 1871 (National Park Service). His assignment in 1873 nested a scientific and touristic ambition inside a military one: the Army wanted a general survey of northwestern Wyoming for defense purposes, and the survey’s planners saw an opportunity to send Jones through Yellowstone itself, in hopes of locating, in his own instructions, a workable route from the south into Montana by way of the Wind River Valley and the upper Yellowstone (National Park Service). A companion purpose, described later by regional historians, was more practical still: a road that might connect the Union Pacific line in southern Wyoming to the park, and beyond it to the developing gold camps of Montana, then reachable chiefly by the long haul from the railroad at Corinne, Utah (Access Genealogy).

Assembling the Column

Jones’s party was a working scientific expedition dressed as a military reconnaissance. Accompanying him was Theodore B. Comstock, a geologist whose observations would later form part of the expedition’s published report, along with topographers, chemists, and an infantry escort sufficient to protect a train of wagons and pack mules through country the Army still regarded as contested (National Park Service; U.S. Army Corps of Engineers). The presence of trained scientists reflected a pattern set by the era’s other great reconnaissances. Ferdinand Hayden’s Interior Department surveys and Captain John Barlow’s 1871 Army expedition had already produced the reports and photographs that helped push Yellowstone’s protection through Congress, and the government intended Jones’s outing to extend that work westward and southward, into ground Hayden and Barlow had not touched (U.S. Army Corps of Engineers).

Guiding the column through the mountains was a Shoshone man named Togwotee, whose knowledge of hunting trails through the Absaroka and Wind River country proved indispensable. According to the Wyoming State Historical Society’s account of Native trail systems in the region, Jones’s northwestern loop carried the party across Blondie Pass in the Owl Creek Mountains, near Sylvan Pass in the Absarokas, and back through the Two Ocean country entirely on the strength of Togwotee’s familiarity with paths that were, to Jones, invisible until his guide found them (WyoHistory.org). The same source notes that Jones had feared the mountains east of Yellowstone Lake might prove impassable, and that he greeted his first sight of the lake from near Sylvan Pass with open relief.

Through the Absaroka

The mountains Jones crossed had no settled English name before his passage. In his own report, quoted on a mountaineering reference devoted to the range, Jones claimed the right to christen them, writing that he had been the first to cross the range and to fix its geographical position and extent, and that he would call them the Sierra Shoshonee (SummitPost). Later usage settled instead on Absaroka, the anglicized form of the Crow people’s name for themselves, but the substance of Jones’s claim has held up: modern accounts of the range’s exploration history continue to credit him as the first officer to survey and document it, decades after the mountain man John Colter had passed through without leaving a systematic record (Roaming Montana; SummitPost).

The crossing itself was treated by later writers as a genuine feat of frontier travel. A regional history of Yellowstone’s early exploration, closely following Hiram Chittenden’s classic institutional history of the park, credits Jones with carrying the first organized party through what it calls the impassable barrier of the Absaroka Range, entering the park near the creek that today bears his name, just east of the northern end of Yellowstone Lake (Chittenden). From that point of entry, the expedition worked its way down the east bank of the Yellowstone River into the valley near Junction Butte, then west to Mammoth Hot Springs, before doubling back over the more familiar tourist route past Tower Creek, Mount Washburn, the Grand Canyon of the Yellowstone, and the geyser basins, then swinging east again toward the lake and the upper Yellowstone River (Chittenden).

Two-Ocean Water and the Pass to Wind River

The expedition’s most enduring discoveries came on its return leg, as Jones pushed east from the lake toward the Continental Divide. Frontier lore had long held that a stream somewhere near the headwaters of the Yellowstone and the Snake split into two channels, one draining eventually to the Atlantic and the other to the Pacific. Jones’s party verified the tradition at what became known as Two Ocean Pass, where Atlantic and Pacific Creeks part ways along a marshy divide barely perceptible on the ground (Chittenden). The National Park Service’s own institutional history of the park’s road system takes its title from this discovery and from the pass Jones found just beyond it, a route over the Continental Divide that Togwotee guided the party through and that has carried his name ever since (National Park Service).

The expedition’s field journal, portions of which survive in the government’s published report, gives some sense of the physical toll of this stretch of the march. An entry for August 2 records a fourteen-mile push across the divide into the Yellowstone basin, over ground so thinly covered with friable volcanic sandstone that the horse hauling the party’s odometer cart, the instrument used to measure distance traveled, broke down entirely and had to be abandoned on the trail (National Park Service). Such details, mundane as they are, illustrate how much of the expedition’s real labor lay not in discovery for its own sake but in the exacting business of measurement: fixing latitude and longitude, estimating elevation, and converting a summer’s hard travel into a map that other travelers, and eventually other soldiers, could trust.

Measuring the Park, and a Question of Accuracy

Jones’s report also included the first documented measurements of the Upper and Lower Falls of the Yellowstone River, though these figures reveal the limits of the instruments available to him. Working from barometric readings rather than direct measurement, Jones’s party set the Upper Falls at roughly 150 feet and the Lower Falls at 328 feet (U.S. Army Corps of Engineers). Two years later, Captain William Ludlow’s reconnaissance through the same country used a weighted, marked cord lowered directly over the falls, a cruder but more direct method that produced figures of 110 and 310 feet, respectively, figures modern surveys have shown to be far closer to correct (U.S. Army Corps of Engineers). The discrepancy is a useful reminder that Jones’s expedition, valuable as it was, produced a first approximation of the park’s geography rather than a finished one; subsequent parties spent the following decade correcting and refining what his survey had begun.

The Route to Montana, and What Came of It

For a Montana readership, the significance of Jones’s march lies less in the scenery he catalogued than in the connection he was sent to establish. His instructions had specifically charged him with finding a road from the Wind River country, through the upper Yellowstone, into Montana Territory, and his published report devoted a separate section to what it called the new Yellowstone route to Montana (National Park Service). That the resulting trail was rough, and that a true wagon road through the same country would not exist for years, did not diminish the interest it generated. The following year, in 1874, a party of Bozeman citizens organized their own commercial and prospecting expedition down the Yellowstone Valley, hoping to open a wagon road linking the region to developing markets and to compete with the advancing Northern Pacific Railroad—an effort that reflected how keenly local communities were looking to secure commercial access throughout the region (Access Genealogy). That Bozeman expedition failed, driven back by Indian resistance and short supplies, but it testified to how quickly early fieldwork and route-finding had entered the practical calculations of Montana’s own settlers.

The government published Jones’s findings as House Executive Document 285 of the Forty-Third Congress’ first session, a report that combined his descriptive journal with separate treatments of the region’s physical geography and meteorology, material that later travelers, surveyors, and eventually park administrators consulted for years afterward (Cramton). Jones himself returned to Yellowstone nearly two decades later, in the early 1890s, this time to oversee the construction and improvement of the park’s roads and bridges, an assignment that placed him, quite literally, in charge of paving over the trail his own pack train had once struggled to find (National Park Service).

An Expedition Among Expeditions

Jones’s march is easiest to understand in the company of the reconnaissances that bracketed it. Captain William Raynolds had tried and failed to reach the upper Yellowstone in 1860, turned back by snow. Hayden and Barlow had surveyed the park’s interior in 1871, laying groundwork for its protection the following year. Jones extended that work outward into the surrounding mountains in 1873, and Ludlow followed two years later with a reconnaissance from Montana’s own Missouri River country, refining measurements Jones had only approximated (U.S. Army Corps of Engineers). Each expedition depended on the ones before it, and each carried forward the same basic institutional purpose: to turn a landscape known chiefly through rumor, guide’s knowledge, and a handful of earlier travelers’ accounts into something the Army, and eventually the traveling public, could navigate with confidence. Jones’s contribution, cutting a first path through what his own report called an impassable range and confirming a road into Montana that regional boosters had only imagined, secured his expedition a lasting place in that larger, collaborative act of mapping the northern Rockies.

Works Cited

“Battle of the Little Bighorn, Montana.” Access Genealogy, https://accessgenealogy.com/montana/battle-of-the-little-bighorn-montana.htm. Accessed 23 Aug. 2026.

“Before Wyoming: American Indian Geography and Trails.” WyoHistory.org, Wyoming State Historical Society, https://www.wyohistory.org/encyclopedia/wyoming-american-indian-geography-and-trails. Accessed 23 Aug. 2026.

Cramton, Louis C. Early History of Yellowstone National Park and Its Relation to National Park Policies. Government Printing Office, 1932. National Park Service, https://www.nps.gov/parkhistory/online_books/yell/cramton/sec8.htm. Accessed 23 Aug. 2026.

“Jones Expedition of 1873.” Absaroka Range. SummitPost, https://www.summitpost.org/absaroka-range/170852. Accessed 23 Aug. 2026.

National Park Service. “Two-Ocean Water and Togwotee Pass: The Jones Expedition of 1873.” Historic Roads in the National Park System, U.S. Department of the Interior, https://www.nps.gov/parkhistory/online_books/baldwin/chap4.htm. Accessed 23 Aug. 2026.

“The Yellowstone National Park: Itex Translation Reports.” Yumpu, https://www.yumpu.com/en/document/view/10733373/the-yellowstone-national-park-itex-translation-reports/85. Accessed 23 Aug. 2026.

Walker, Paul K. Introduction. Exploring Nature’s Sanctuary: Captain William Ludlow’s Report of a Reconnaissance from Carroll, Montana Territory, on the Upper Missouri to the Yellowstone National Park, and Return, Made in the Summer of 1875, by William Ludlow, Engineer Historical Studies no. 3, U.S. Army Corps of Engineers, 1976, https://www.publications.usace.army.mil/portals/76/publications/engineerpamphlets/ep_870-1-22.pdf. Accessed 23 Aug. 2026.

Wyoming Historical Society. “Annals Index - J.” Annals of Wyoming, https://wyshs.org/publications/annals-of-wyoming/index/j. Accessed 23 Aug. 2026.