An early result of the 1870 exploration into the Yellowstone wilderness was the interest it developed among scientists. The first evidence of this was the mention, soon after the Washburn party’s return, that their discoveries were likely to lead to an early exploration of the Yellowstone region “under the patronage of the general Government and the Smithsonian Institute, [sic] and other prominent institutions of the country.” 
Just how Ferdinand V. Hayden and his U.S. Geological Survey of the Territories came to be the agency through which that prognosis was fulfilled is unknown, but it would appear to be only a logical result of his success in resisting the adverse and stultifying influence of Commissioner Joseph S. Wilson, of the General Land Office.  Through the support given him by those scientists whose spokesman was Spencer Baird of the Smithsonian Institution, and his friends at the national capital (these included James G. Blaine, Speaker of the House after March 1869, and Henry L. Dawes, Chairman of the House Committee on Appropriations), Hayden’s position in the Department of the Interior was greatly improved and his organization was favored with increased means—$40,000 provided under the Sundry Civil Act for the fiscal year beginning July 1,1871. 
The conditions under which Hayden was to do his field work in 1871 were spelled out in a letter of instruction from the Secretary of the Interior:
In accordance with the act of the third session of the 41st Congress, making appropriations for the continuation of the Geological Survey of the Territories of the United States, dated March 4, 1871, you are appointed U.S. Geologist, to date from the first day of July, 1871, with a salary of four thousand dollars per annum [an increase of $1,000]. You will be permitted to select your own assistants who will be entirely subject to your orders, and all your expenditures of the public funds are expected to be made with judicious economy and care.
The area of your explorations must be, to some extent, discretionary, but in order that you may continue your labors of preceding years, geographically, your explorations of the present season will be confined mostly to the Territories of Idaho and Montana. It is probable that your most available point of departure will be Salt Lake City, proceeding thence northward along the mail route as a base to Helena, Montana, and completing the season’s work about the sources of the Missouri and Yellow Stone rivers. You will be required to make such instrumental observations, astronomical and barometrical, as are necessary for the construction of an accurate geographical map of the district explored, upon which the different geological formations may be represented with suitable colors.
As the object of the expedition is to secure as much information as possible, both scientific and practical, you will give your attention to the geological, mineralogical, zoological, botanical, and agricultural resources of the country. You will collect as ample material as possible for the illustration of your final reports, such as sketches, sections, photographs, etc.
Should your route lead you in the vicinity of any of our Indian tribes, you will secure such information in regard to them as will be useful to this Department, or the Country. It is desirable that your collections in all Departments shall be as complete as possible, and you will forward them to the Smithsonian Institution to be arranged according to law.
You will he expected to prepare a preliminary report of your labors, which will be ready for publication by Jan’y 1,1872. 
Though Hayden was unable to draw upon his appropriation until July 1, the beginning of the fiscal year, he was still able to assemble and equip his expedition with the help of the Army and the railroads.
Immediately upon the passage of the Sundry Civil bill, Hayden applied to the Secretary of War for permission to draw on the equipment, stores, and transportation at frontier army posts. This was authorized, together with a small escort “when deemed necessary and the public service will permit.”  Likewise, the Union Pacific and Central Pacific Railroads agreed to carry Hayden’s men and equipment without cost. Thus, his experienced assistant, James Stevenson, was able to outfit at Fort D. A. Russell (near Cheyenne, Wyo.) and transport the equipment, subsistence, wagons, and animals he needed by rail to Ogden, Utah, where a base camp was established in mid-May on an old lake terrace a mile east of the city. During the following weeks, the scientists, young men, and. old frontiersmen who were to make up the party gathered there.
Hayden’s party eventually included, in addition to Managing Director Stevenson, Henry W. Elliot, an artist; Professor Cyrus Thomas, agricultural statistician and entomologist; Anton Sch&omul;nborn, chief topographer, a veteran of the prewar Corps of Topographical Engineers; A. J. Smith, assistant topographer; William H. Jackson, an Omaha photographer attracted to the Hayden Survey the previous year; George B. Dixon, assistant photographer; J. W. Beaman, meteorologist; Professor G. N. Allen, botanist; Robert Adams, Jr., assistant botanist (later United States Minister to Brazil and a member of Congress from 1893 to 1906); Dr. A. C. Peale, mineralogist (also a medical doctor and a grandson of the naturalist, Reubens Peale); Dr. Charles S. Turnbull, physician and general assistant; Campbell Carrington, zoologist; William B. Logan (son of Representative John A. Logan of Illinois), secretary; F. J. Huse, Chester M. Dawes (son of Representative Henry L. Dawes of Massachusetts), D. Dev. Negley, and J. W. Duncan, all general assistants. 
While the members of his party were assembling at Ogden, Hayden received a letter from Capt. John W. Barlow, chief engineer of the army’s Division of Missouri, informing him that,
Genl Sheridan desires me to join your party previous to its entering the “Great Basin” of the Yellow Stone lake—and I am greatly delighted at the prospect of seeing the wonders of that region under such favorable auspices. 
In this correspondence, which was intended to arrange a time and place at which he could join Hayden’s expedition, Barlow added:
I had determined some time ago to endeavor to make an excursion into that country this summer taking a small party along, but as you are to make such a thoroughly exhaustive examination there will probably be no occasion for undergoing the expense of a second expedition of like magnitude.
About the time the expedition began its northward trek, Hayden received a letter from Jay Cooke’s office manager asking him to take a guest into the Yellowstone region. He was speaking for the artist Thomas Moran, who was introduced thus:
—my friend, Thos. Moran, an artist of Philadelphia of rare genius, has completed arrangements for spending a month or two in the Yellowstone country, taking sketches for painting. He is very desirous of joining your party at Virginia City or Helena, and accompanying you to the head of the Yellowstone. I have encouraged him to believe that you [would] be glad to have him join your party, & that you would in all probability extend to him every possible facility. Please understand that we do not wish to burden you with more people than you can attend to, but I think that Mr. Moran will be a very desirable addition to your expedition, and that he will be almost no trouble at all, and it will be a great accomodation to both our house [Jay Cooke & Co.] & the road, if you will assist him in his efforts. He, or course, expects to pay his own expenses, and simply wishes to take advantage of your cavalry escort for protection. You may also have six square feet in some tent, which he can occupy nights. Please write on receipt of this saying what you can do in the way of accomodating him, so that he may know what to take with him, & what to leave behind.
It is possible, also, that Bierstadt may join you in Montana, before you start for the Yellowstone, but this is only a possibility. Mr. Moran will possibly go to Corinne by rail, & then cross over by stage to Helena in time to join you there. 
While enroute to the Yellowstone region, Hayden received a letter from his scientific mentor at the Smithsonian Institution, Spencer Baird, confirming the wisdom of the plan under which the field work was being conducted. He wrote: “I think your plan of operations is good, and you will make more capital and accomplish more for science by concentrating effort upon some one region like the Yellow Stone, than by attempting to traverse an immense section of country.” 
The plan pursued in the prosecution of the field work during the 1871 season was outlined by Hayden in his letter to the Secretary of the Interior, on the eve of the departure from “Camp Stevenson,” the base camp near Ogden, Utah. In it he wrote: 
Our route will be along the mail route to Virginia City, and Fort Ellis. We have already made the necessary observations in this valley and propose to connect our work Topographical and Geological with the Pacific Rail Road line. We then propose to examine a belt of country, northward fifty to one hundred miles in width to Fort Ellis, which point we hope to reach about the 10th or 15th of July. The remainder of the season we desire to spend about the sources of those rivers—Yellowstone, Missouri, Green, and Columbia,  which have their sources near together in this region.
Captain Barlow’s plans matured at this time. In his letter thanking Hayden for “your very cordial invitation to suit my own convenience in joining your party,” the captain mentioned that Gen. A. A. Humphreys, Chief of Engineers, had provided financial assistance from the appropriation for surveys, and had suggested he take several assistants with him. He planned to bring Capt. David P. Heap, engineer officer of the Department of Dakota, and “two or three others . . . possibly I may take along a photographer for obtaining views.”  He intended to organize a small pack train at Fort Ellis and regulate his movements beyond that point so as to share the escort allowed Hayden’s party (a factor which may have caused the latter group to abandon the proposed exploration of Snake River for that season).
The progress of the expedition was reported to the Secretary of the Interior in four letters. The first, written July 18 from Bottler’s ranch, on the Yellowstone River,  reported the establishment of a base camp at that point, beyond which the wheeled vehicles could not be taken. There had been no misfortunes, and Captain Barlow was then a day behind with the escort (Troop F, Second Cavalry). Hayden was able to add: “We have explored a most interesting belt of country from Ogden to this point, observations for the Topography, Geology and Natural History have been made. We found all the maps, official and otherwise, utterly inadequate to travel by.”
Hayden’s second letter from the area he was exploring was written at Yellowstone Lake on August 8, 1871,  following his return from a side trip to the geyser basins on Firehole River. Of his progress within the Yellowstone wilderness he wrote;
. . . made a pretty careful examination of the Geyser region, Map of the whole region, Charts of the Springs and Geysers, with temperatures of each. Sketches, Photographs etc. I have made quite thorough soundings of the Lake,  explored the north and west sides and will now move to the south and east sides. We are making a good topographical and geological map of the entire district.
At this point Lieutenant Doane arrived to take over the escort from Captain Taylor.
Hayden’s letter of August 28, again from Bottler’s ranch, reported that his survey of the Yellowstone region had been completed without misadventure, so that he felt justified in saying, “no portion of the West has been more carefully surveyed than the Yellow Stone basin.” 
A final letter from the field, written at Fort Hall on September 20, mentioned the mapping of a belt of country along the return route of his party and set October 1 as the date for the termination of work at Fort Bridger, Wyo.
Meanwhile, Captain Barlow (who had arrived at Fort Ellis on July 12 with Captain Heap and three assistants) had managed to outfit his party in 2 days and move out behind Hayden. Though the two groups shared a common escort, they continued that tandem movement, proceeding through the Yellowstone wilderness a day or two apart but not always by the same route.
Captain Barlow’s smaller party concentrated on topographical work, its particular contribution being tile establishment of the latitude and longitude of a sufficient number of points to provide the “control” for accurate mapping of the area—a groundwork which served as a fitting conclusion to the exploratory period. Barlow’s photographer made what would have been a significant pictorial record had the negatives survived the great Chicago fire.
Both parties suffered reverses following their return to civilization. Hayden’s stemmed from the death of his topographer, Anton Schönborn, who took his own life at Omaha on the return to Washington, D.C. This was a lesser calamity than at first supposed because personnel of the U.S. Coast Survey were later successful in interpreting the dead man’s field notes.  While the resulting map was undoubtedly something less than it might have been, it served Hayden’s immediate purpose-as an illustration in his report, and as a base on which to delimit the proposed national park (see map 13). 
Captain Barlow’s calamity was beyond remedy. The fire which leveled most of Chicago on October 8-11, 1871, also destroyed the headquarters of the Military Division of the Missouri, and with it much of the results of the expedition from which Barlow had just returned. In a letter to Hayden, he explained,
You will sympathize with me I know when I tell you that our great fire swept away all my photographic plates before prints were taken from them. Only 16 prints were made on Saturday previous to the fire, these 16 Mr. Hine had taken to his house & saved. I lost some of my notes also, though my journal was saved from which I can make a report. The map notes were up at St. Paul & Capt. Heap has sent me a sketch of our route. As we only partially surveyed the Lake (knowing that you were doing so with great care) I depended upon your work in that particular, & hope to receive a copy of your map very soon . . . I shall have to trust to our old friendship & your generosity, now, respecting an exchange of photographic views. I can only offer you 16 copies, instead of near 200, that I expected to have had. Not one single paper or other property was saved from my office. All my instruments, maps, books, & everything brought back from the Yellowstone, including specimens were consumed. I have had to begin all anew. 
Hayden was able to send 100 large prints and an equal number of stereoscopic views as samples, from which Captain Barlow was to pick the photographs he needed. It was necessary for the latter to deal directly with William H. Jackson to obtain his prints because the photographer had retained all the negatives as a condition of employment.  Captain Barlow desired the photographs for distribution with his report,  and for illustrating the several articles General Sheridan urged him to write.
But General Sheridan was not alone in urging an exposé; Thomas Moran’s presence with the Hayden contingent was dictated by Scribner’s need for illustrative material for yet another Yellowstone article by N. P. Langford (who had been expected to accompany the 1871 expedition in the interest of J. Cooke & Co.). However, Langford was either unable or unwilling, so editor R. W. Gildess found it necessary to write Hayden at Fort Hall, admitting they were “at sea for some literary accompaniment” for Moran’s sketches (he had returned to the East early). The question put to Hayden was, “Can you do it for us?” The editor wanted something within a month; if that were not possible, “could you do it for us when you get back to Washington?”  It had to be the latter, and it was published in time to be very helpful in bringing the effort to establish Yellowstone Park to a successful conclusion.
The 1871 exploration received an immediate and enthusiastic notice in the press. As the Helena Daily Herald said, “The results of the observations and examinations of the late scientific expedition, will soon be given to the public by press, and through it excite a curiosity and interest, which the wonders of Vesuvius, Niagara, and the geysers of Iceland, have never yet caused to be felt.”  Less than a week later the New York Times, while anticipating “trustworthy, exact, and comprehensive . . . information of one of the most wonderful tracts of the American continent,” stated:
There is someting romantic in the thought that, in spite of the restless activity of our people, and the almost fabulous rapidity of their increase, vast tracts of the national domain yet remain unexplored. As little is known of these regions as of the topography of the sources of the Nile or the interior of Australia. They are enveloped in a certain mystery, and their attractions to the adventurous are constantly enhanced by remarkable discoveries. . . . Sometimes, as in the case of the Yellowstone Valley, the natural phenomena are so unusual, so startlingly different from any known elsewhere, that the interest and curiosity excited are not less universal and decided. 
Something of the persistent skepticism with which information concerning the Yellowstone region was received is evident in an item subsequently published in the same columns. Under the title, “The New Wonderland” (probably the first published use of the term “wonderland” to typify what is now the park), the Times made the following comment in regard to the information received from the expedition’s artist, Henry Elliot:
The accounts of the Yellowstone country hitherto received, even when brought by authorities so respectable as Lieut. Doane, have been so extraordinary that confirmatory testimony has been anxiously looked for. Even now, and with every respect for the new witness, part of whose evidence we shall quote, the official narrative of the Hayden Expedition must be deemed needful before we can altogether accept stories of wonder hardly short of fairy tales in the astounding phenomena they describe. 
But regardless of the lingering skepticism, the information obtained in 1871 was reaching the reading public from one side of the Nation to the other. Comments and narratives stemming from expedition personnel appeared in the Boston Advertiser (Massachusetts), the Cleveland Herald (Ohio), the Omaha Herald (Nebraska), and the Sacramento Bee (California). Leslie’s Illustrated for September 31, 1871, carried an article by Henry Elliot—spoken of as “our artist.” 
However not all the publicity generated at this time originated with the Hayden and Barlow parties. Truman C. Everts’ article in Scribner’s Monthly (November, 1871) was a holdover from the expedition of 1870  and a series of articles which appeared in the Deer Lodge New North-West (Montana) resulted from a visit by a party that entered the Yellowstone region from the west in August.  This group, which included U.S. Mining Commissioner R. W. Raymond; his assistant, a Mr. Eiler; A. F. Thrasher, a Virginia City photographer; J. S. Daugherty, an Indiana business man traveling for his health; C. C. Clawson, a reporter and author of the “Notes,” and Gilman Sawtell, settler at Henry’s Lake and guide, were the vanguard of that tourism which, a century later, swelled to more than 2 million persons annually.
There were other signs of the end of the period of definitive exploration, among them the appearance of settlers within the Yellowstone region. The Hayden and Barlow parties found intrusions at three points. On Gardner River, near the great outflow of hot water that had caused the prospectors to name it “Warm-Stream Creek,” they found a haphazard encampment of invalids who called their rude spa “Chestnutville”—a place Matthew McGuirk claimed that fall and developed into “McGuirk’s Medicinal Springs.”  Upon the hot spring terraces then generally known as “Soda Mountain,” two Bozeman men had laid claim to the hot springs and built a cabin.  They were Harry Horr, the same who had accompanied the springwagon sent up to Yankee Jim Canyon to convey the rescued Truman C. Everts out of the wilderness, and James C. McCartney. Jack Baronett, whose rescue of Everts had gained him nothing but the inspiration to build a toll bridge over the Yellowstone River on the road to the new mines on Clark Fork (the present Cooke City area), had control of a site at the mouth of Lamar River. His was the first bridge to span the Yellowstone River at any point. 
One of the men bathing at “Chestnutville” (Hot River) when Hayden and Barlow arrived was A. Bart Henderson, whose diary entry for July 24, 1871, notes:
Left camp at 9 o’clock & followed down the river. Arrived at Bottlers Ranch. Here I remained a few days, resting and viewing out a road which I located on the 12 day of Aug. 1871. It is to run from Bozeman to the Yellowstone Lake, by the Mammoth Hot Springs, built for the benefit of the travel to & from Wonderland, & to be a toll road. I soon commenced work on the same . . . 
Even before the explorers of 1871 turned homeward with their notes and specimens, the process of subduing the Yellowstone wilderness had been begun in the style of the American frontier—by raising cabins and building roads within its fastnesses, and surely it would have gone the way of many another pristine locality except for a letter that came to Dr. Hayden in the City of Washington.