Charting the Unknown:

Isaac I. Stevens and the 1853 Northern Pacific Railroad Survey Through Montana

Introduction: A Commission with Two Purposes

In the spring of 1853, a column of nearly two hundred men departed St. Paul, Minnesota, bound westward into territory that the federal government had never systematically mapped. The man at the head of the column, Isaac Ingalls Stevens, carried two simultaneous appointments from President Franklin Pierce. He was the first governor of the newly created Washington Territory, traveling to assume his post. He was also the superintendent of the most ambitious government-sponsored exploration of the American interior since the Lewis and Clark Expedition — the northern survey for a Pacific railroad. The dual commission was not a coincidence but a design: Stevens embodied the federal government’s interlocking ambitions of territorial governance, Indigenous dispossession, and continental economic integration. The survey he led through what would become Montana left a record of scientific inquiry, diplomatic encounter, and cartographic ambition that shaped the region’s trajectory for generations.

Background: Congress Authorizes the Surveys

The pressure to build a transcontinental railroad had been building for years before the 1853 legislation that authorized the surveys. Asa Whitney, a New York merchant with interests in Pacific trade, had lobbied Congress for an overland rail route as early as 1846. His proposal failed, in part because sectional disagreements over the railroad’s course reflected the deepening divisions over slavery and western land. The Mexican-American War’s settlement in 1848 added 525,000 square miles of western territory to the United States and sharpened the urgency of connecting East and West. The California gold rush of 1848 and subsequent population surge on the Pacific coast made the question of a transcontinental link not merely commercial but strategic.

On March 3, 1853, Congress appropriated $150,000 and directed the Secretary of War, Jefferson Davis, to identify the most practical and economical route for a railroad from the Mississippi River to the Pacific Ocean. Davis dispatched survey parties along four primary corridors, corresponding roughly to the thirty-second, thirty-fifth, thirty-eighth, and forty-seventh to forty-ninth parallels. Stevens received command of the northernmost survey, the route along the forty-seventh and forty-ninth parallels. The political logic of the assignment was transparent: Davis, a Mississippian with strong southern sympathies, favored a southern route and placed the northern survey in the hands of a man who had the institutional incentive, as incoming territorial governor, to produce a favorable report for the northern corridor. Stevens understood the stakes and pursued his mandate with characteristic intensity.

The Expedition: Organization and Personnel

Stevens spent the spring of 1853 assembling his party in Washington before moving to organize logistics at St. Paul. The expedition was divided into eastern and western divisions that would survey simultaneously from opposite ends of the route before converging at the Columbia Basin. Stevens personally commanded the eastern division and set out from St. Paul in June 1853. His party included military officers, civilian engineers, naturalists, physicians, artists, and guides — a cross-section of the scientific and institutional infrastructure that the federal government brought to bear on western exploration in the antebellum period. Among the scientific personnel was George Suckley, a physician and naturalist appointed as assistant surgeon to the expedition, whose work on the natural history of the northern corridor produced findings that were later transmitted to the Smithsonian Institution. Suckley’s papers, held today at the Merrill G. Burlingame Special Collections at Montana State University in Bozeman, include original correspondence with Stevens from October 1853 and record the detailed orders Stevens issued as the party moved through present-day Montana. Two artists, John Mix Stanley and Gustavus Sohon, produced the visual record of the survey. Stanley’s lithographs, later published as part of the official reports, included scenes from the Bitterroot Valley and the approaches to Cadotte’s Pass that constitute some of the earliest published images of the Montana landscape.

The route followed by the eastern division ascended the Missouri River to Fort Union at the confluence of the Yellowstone and Missouri Rivers, then pressed westward across what would become Montana. The party traveled through the high plains of the Missouri drainage, passing Fort Benton — the head of reliable steamboat navigation on the Missouri — before approaching the Rocky Mountain front. The second map of the survey’s published set, covering the full width of present-day Montana, noted established landmarks including the Bear’s Paw Mountains, the Judith Mountains, and the Little Rocky Mountains, while also recording the routes of earlier reconnaissance parties and the locations of trading posts including Fort Union and Fort Benton.

Montana Terrain: The Problem of the Passes

The central technical question facing the northern survey in Montana was the Continental Divide. A railroad route was only commercially viable if the grade over the mountains was gentle enough to permit efficient operation. The passes of the northern Rockies were poorly documented by American sources, and Stevens understood that Indigenous knowledge would be indispensable to locating them. The two passes that received the most systematic attention during the 1853 survey were Cadotte’s Pass and the elusive Marias Pass.

Cadotte’s Pass, known to fur traders and to Salish guides, was crossed by the main survey party in September 1853 and recorded in Stanley’s lithographs. John Mullan, Stevens’s chief engineering lieutenant, conducted a parallel reconnaissance from Fort Benton southwestward, guided at different points by Piegan Blackfeet and Salish scouts. Mullan crossed the Continental Divide through what he called Hell Gate Pass in late September 1853 and descended through the Little Blackfoot River drainage to reach the Missoula Valley, where he rendezvoused with the main party at Fort Owen near present-day Stevensville on September 30, 1853. The information Mullan’s sub-party gathered about the mountain geography of central Montana was incorporated into the survey’s final reports.

The question of Marias Pass proved more complicated. Stevens had received indications that a low, broad pass existed somewhere along the Marias River drainage that would offer a dramatically easier crossing of the Continental Divide than any alternative so far identified. In his journal entry of September 5, 1853, Stevens described dispatching Frederick Lander to investigate what he believed to be the most promising solution to the Rocky Mountain passage. A few days later, at a Piegan encampment near the Marias River, artist John Mix Stanley met with Piegan leaders including the chief Little Dog, described in the survey’s official report as a man of considerable standing and reliability. Stevens recorded that Little Dog provided a detailed description of the Marias Pass: a broad, open valley with minimal obstruction except for fallen timber, which had formerly served as the primary Blackfoot crossing between the plains and the western slopes but had fallen out of use due to tribal custom. The knowledge Stevens obtained from the Piegan was specific and accurate, anticipating by decades the pass’s formal charting by Great Northern Railway engineer John Frank Stevens in 1889.

Aware that the season was too advanced for a crossing attempt, Stevens dispatched his civilian engineer Abiel W. Tinkham northward through the Flathead Valley in October 1853 with a Flathead Indian scout, instructing him to locate the pass from the west. Tinkham completed the traverse but crossed Cut Bank Pass rather than the true Marias Pass, a navigational error that would not be corrected until the following survey season. In the spring of 1854, Stevens sent John Doty east from Fort Benton with Hugh Monroe, a former Hudson’s Bay Company employee who had lived among the Piegan, to approach Marias Pass from the plains. Doty came within sight of the pass but did not complete the crossing. Stevens reported Doty’s results in his final submission to Congress with evident frustration that the definitive confirmation of Marias Pass remained elusive.

Indigenous Encounters and Their Consequences

The Stevens survey’s passage through Montana was not simply a technical exercise. The expedition moved through the territories of multiple Indigenous nations — the Blackfoot Confederacy on the northern plains and Rocky Mountain front, the Bitterroot Salish in the western valleys, the Pend d’Oreilles, and others — and Stevens understood from the outset that his mandate as governor of Washington Territory included negotiating treaties that would clear the way for settlement and for a railroad. The survey’s encounters with Indigenous peoples in 1853 were, in this respect, reconnaissance of a different kind: Stevens was assessing not only terrain but the political landscape he would need to reorganize.

On September 9, 1853, Stevens dispatched Mullan on a diplomatic mission to the Salish nation, carrying messages intended to establish peaceful relations and set the groundwork for future treaty negotiations. The Hudson’s Bay Company had previously issued instructions to its personnel to extend courtesies and assistance to Stevens’s party, a logistical accommodation that also signaled the extent to which the survey moved through territory where existing trade networks and Indigenous political structures were the primary organizing frameworks. Two years after the survey’s conclusion, Stevens returned to Montana to negotiate the Hellgate Treaty of 1855, signed by the Bitterroot Salish, the Pend d’Oreilles, and the Kootenai at Council Grove near the confluence that would later become Missoula. The 1855 treaty confined those nations to the Flathead Reservation and opened the survey corridor to settlement. The survey of 1853 and the treaty negotiations of 1855 were, in this sense, sequential phases of the same federal project.

Scientific Contributions: Natural History and Cartography

The Stevens survey’s scientific legacy extended well beyond the railroad question. The naturalists attached to the expedition produced biological collections that were transmitted to the Smithsonian Institution and contributed to the systematic documentation of western North America’s flora and fauna. George Suckley’s eastern division work included the identification of three new species and one new genus along the Missouri River corridor. The official published reports of the survey, which appeared in twelve volumes between 1855 and 1860 under the title Reports of Explorations and Surveys, to Ascertain the Most Practicable and Economical Route for a Railroad from the Mississippi River to the Pacific Ocean, contained illustrated plates of botanical specimens, mammals, birds, fish, reptiles, and insects collected during the expedition. Stevens’s own narrative report on the northern route appeared in Volume XII.

The cartographic output was equally significant. Stevens’s preliminary survey map, published in 1855 and corrected by the Office of Pacific Railroad Surveys, covered the route in three sheets spanning from St. Paul to Puget Sound. The Montana sheet documented mountain ranges, river systems, and the locations of trading posts with a level of detail unprecedented in American cartographic records of the region. The map incorporated information from earlier fur trade expeditions and from Indigenous informants alongside the survey party’s direct observations. The Library of Congress holds original copies of this preliminary survey map, which stands as one of the earliest systematic cartographic representations of what would become Montana.

The Reports and Their Aftermath

Stevens submitted his official report to Congress in 1855, arguing that the northern route was not only practicable but superior to the alternatives. His case rested on the relative gentleness of the grades through the passes he had identified and on the economic potential of the territories through which the route would pass. The report’s reception was shaped by the political environment of the mid-1850s. Jefferson Davis, who had organized the surveys, used the collected reports to argue in favor of the southern route, which he characterized as the most economical. The northern survey’s results were not dismissed, but they did not produce the immediate outcome Stevens had anticipated. Congress did not authorize a transcontinental railroad on any route before the Civil War; the sectional crisis that had complicated the railroad debate since the 1840s ultimately prevented a consensus.

The northern route Stevens had charted would eventually be built. The Northern Pacific Railroad reached Montana in the 1880s and completed its transcontinental connection in 1883, following a corridor broadly consistent with what Stevens had surveyed. The Great Northern Railway, built by James J. Hill without federal land grants, opened its line through Montana in the early 1890s and crossed the Continental Divide via the Marias Pass that Stevens had identified from the Piegan chief Little Dog in 1853 but never formally mapped. A statue of Isaac Stevens stands today at the summit of Marias Pass.

Conclusion: Legacy and Limits

The 1853 Stevens survey occupied a pivotal position in Montana history precisely because it was neither purely scientific nor purely political but both simultaneously. It produced a documentary record — cartographic, biological, and ethnographic — of a landscape that had been occupied and managed by Indigenous peoples for thousands of years but was largely unknown to the American federal government. It also set in motion processes of dispossession and settlement that fundamentally altered the conditions of life for every Indigenous nation in the survey corridor. The survey’s scientific achievements were genuine, but they served a project whose consequences fell very unevenly on the peoples of what became Montana.

As a work of exploration, the survey represented what historian William H. Goetzmann characterized as the systematic application of military science to the opening of the West — an exercise in which the Corps of Topographical Engineers functioned as an instrument of national expansion as much as of knowledge. The survey’s published reports reached Congress, the Smithsonian, and eventually the reading public; the Indigenous knowledge that made the survey possible, from Little Dog’s description of Marias Pass to the Salish guides who led Mullan across the divide, appeared in those reports as data without attribution. What the survey’s participants encountered in Montana in 1853 was not an empty landscape awaiting description but a complex, inhabited geography — one that the survey transformed, in the federal record, into a corridor available for rails.

Works Cited

Goetzmann, William H. Army Exploration in the American West, 1803-1863. Yale University Press, 1959.

Haney, Austin. “Iron Dreams: Montana and the Pacific Railroad Surveys of 1853.” Humanities Montana, 2024, www.humanitiesmontana.org/programs/iron-dreams-montana-and-the-pacific-railroad-surveys-of-1853/. Accessed 3 May 2026.

Hassrick, Peter H. “John Mix Stanley: An Artist’s View of the 1853 Pacific Railroad Survey and the Far Northwest.” Montana: The Magazine of Western History, Montana Historical Society, vol. 63, no. 1.

Isaac I. Stevens Papers, 1840-1862. Archives West, Orbis Cascade Alliance, accession 111-1, archiveswest.orbiscascade.org/ark:/80444/xv04454. Accessed 3 May 2026.

“Stevens Pacific Railroad Survey.” Smithsonian National Museum of Natural History, naturalhistory.si.edu/research/botany/about/historical-expeditions/stevens-pacific-railroad-survey. Accessed 3 May 2026.

Stevens, Isaac I. Narrative and Final Report of Explorations for a Route for a Pacific Railroad, Near the Forty-Seventh and Forty-Ninth Parallels of North Latitude, from St. Paul to Puget Sound. Vol. 12, Book 1 of Reports of Explorations and Surveys, to Ascertain the Most Practicable and Economical Route for a Railroad from the Mississippi River to the Pacific Ocean. Thomas H. Ford, Printer, 1860.

Stevens, Isaac Ingalls, and Northern Pacific Railroad Company. Preliminary Sketch of the Northern Pacific Rail Road Exploration and Survey, by I. I. Stevens, Governor of Washington Territory. Philadelphia, 1855. Map. Library of Congress, Geography and Map Division, www.loc.gov/item/98688746/. Accessed 3 May 2026.

Suckley, George. George Suckley Papers, 1853-1863. Merrill G. Burlingame Special Collections, Montana State University Library, Bozeman. Finding aid: Archives West, archiveswest.orbiscascade.org/ark:/80444/xv41961. Accessed 3 May 2026.

“Train Trips to Paradise: The Railroad Transformed Montana.” University of Montana, www.umt.edu/this-is-montana/columns/stories/the-railroad-transformed-montana.php. Accessed 3 May 2026.

“We’ve Been Working on the Railroad!: The Stevens Expedition.” Historical Museum at Fort Missoula, Scalar, University of Southern California, scalar.usc.edu/works/weve-been-working-on-the-railroad/what-was-the-stevens-expedition. Accessed 3 May 2026.