On forty different sunrises during December, January, and February (plus two more in March), temperature readings at Fort Mandan sank below zero. The most frigid day, though not by much, was December 17: 45°F below at sunrise and 28° below at 4:00 P.M. All sunrise temperatures from January 5, 1805, through January 15 were –10° or lower; –48°, – 38°, – 36°. The average for the three-month period was four degrees above zero. For comparison: during the thirty-year span from 1951 through 1980, the average temperature for the same months in the same general area was 12.3° above zero—roughly twenty degrees below freezing. Even granting the likelihood that the Corps's thermometers were less precise than modern ones, the winter at Fort Mandan was remarkably chilly. 
Double suns shone in the southern sky. One night the moon wore halos and bars. Moisture in the air occasionally froze into a floating murk that resembled fog. When breezes were gentle—not often—frost collected in deep rinds on the barren limbs of the trees. Then a rising wind would shake the boughs and the frost crystals would fall like snow from a bright blue sky. Sometimes one of the cottonwoods Clark had described as full of water would explode with a boom like a cannon shot. Gales roared with discouraging frequency, sweeping the plains bare except for ridges of drifted snow that lay like welts across the earth.
On December 7, Big White galloped to the fort, shouting and pointing. Shaggy buffalo, seeking relief from the chill of a violent northwest wind, were streaming off the plains and down the slopes of the river trench into the timber-filled bottomlands. Village hunters were gathering for the kill, but would hold back until the whites joined them.
During the next bitter week Lewis and Clark took turns leading detachments of the Corps into the numbing cold to join the slaughter. Afoot, they watched enviously as mounted Indians armed with bows and arrows surrounded a number of buffalo and eased them out of the trees onto the terraces or into clearings where their excited horses could maneuver. Each rider chose a quarry, ran his horse up beside the ponderously galloping beast, and with his powerful bow drove an arrow all but out of sight into its flesh. The Mandans killed about twenty that first day, twice as many as the whites, hunting among the trees, brought down with their rifles. Three that members of the Corps felled were shot within sight of the fort. One of the trio, a cow, leaped off the bank onto the ice, broke through, and died in the "vacancy" as Clark expressed it. Somehow the men got a rope braided out of elk hide around the animal, dragged her to the boat landing, and butchered her there. She was pregnant. Cutting the fetus free, the whites gave it to the wives of the interpreters who cooked and ate it with zest. 
Of the ten buffalo the whites killed, they were able to butcher and lug back to the fort only five before darkness fell. Wolves and Indians claimed the other five. To increase the speed of retrieval—the buffalo were drifting farther away from the fort—the captains bought one packhorse and rented three from the Mandans. Even so, they did not recover nearly as many animals as the hunters killed. The below-zero cold made quick butchering impossible, and predators devoured whatever was left unattended for long. To protect some of the spoils Meriwether Lewis and then William Clark, on separate occasions and accompanied by a few men, shivered out the darkness beside the inert mounds of flesh.
Casualties among the enlisted men were high—frosted feet, hands, faces, and in York's case a nipped penis, presumably incurred while he was relieving himself. But there was no telling when buffalo would come as close again, and so the Corps stayed stubbornly with the hunt until December 12, when the sunrise temperature was – 38°F. The hunters still out were called back, and for the next few days the men ventured away from the fort only to gather firewood on their hand-drawn sleds. Their great dislike was sentry duty on the rooftop, even though turns were limited to half an hour each during the coldest weather.
As temperatures rose, the buffalo drifted back to their grazing on the high plains. The men resumed cutting timber and building a wall of massive pickets across what had been the open end of the fort. Crowds of Mandans came by to visit, often making nuisances of themselves by pilfering small articles and importuning the captains to exchange trade goods for corn. This presented Lewis and Clark with a dilemma. The merchandise in the storerooms had to be used as good-will offerings for Indians as far away as the Pacific. Yet if the buffalo stayed away the Corps would need the Mandans' dried vegetables as a source of food. How could they get the provisions without jeopardizing their own future?
An unnamed entrepreneur devised a solution. Why not let William Bratton and Alexander Willard, who knew something of blacksmithing, and John Shields, who was both a blacksmith and an expert gunsmith, offer to repair and/or sharpen the relatively few metal objects the Mandans had collected from British traders over the years—hoes, skinning knives, kettles, and occasional fire-arms—in exchange for agreed-on measures of corn and dried vegetables? The idea took hold. Sergeant Gass supervised the building of a covered pit in which wood could be reduced to charcoal; on the day before Christmas the blacksmiths set up the forge and bellows, which until then had been seldom used.  The Indians thronged around open-mouthed. Magic!
Work did not begin on Christmas, however. The Mandans were asked to stay their distance, since that was a great "medicine day" for the whites, though if any religious activity did take place, that fact, too, goes unrecorded. (There is no indication that any group worship of any kind was ever held during the course of the expedition.) Shortly before sunrise, the enlisted men and the discharged French who were living in a nearby hut woke the captains with volleys of rifle shots. A flag was raised, the swivels boomed, and Clark passed out rum that was gulped down before breakfast. There was a special feast—bread baked from a limited supply of flour, pies made of dried apples, pepper for spicing the steaks, and more rum. One of the rooms was cleared for dancing, Cruzatte tuned his fiddle, and the frolic began. Bored after a time, a few of the men went hunting. By nine in the evening everyone was ready for bed, as tired as if they had been working all day.  On New Year's Day, 1805, there was another celebration. At the request of the chiefs of Matootonha and with the captains' permssion, Ordway and Charbonneau led sixteen men across the river ice to the Indian village. They took with them "a fiddle & a Tambereen & a Sounden Horn"—a bugle. They fired a rifle salute outside the village, were invited in, and fired another volley in the plaza. The townspeople were enthralled by their dancing, as were all Indians they met. One of the Frenchmen jigged while standing on his hands.
Not wanting to put a damper on the fun, the captains stayed at the fort, but when word arrived of an altercation, Clark went up with York, Jessaume, and an unnamed soldier. Whatever the problem, it was over when he arrived, and the merriment was going strong. York added to it with a solo performance that drew resounding applause. At sunset the whites returned to the fort except six who asked for and were granted permission to stay the night. Those six learned, among other things, that during cold weather each Mandan family stabled its best horses in its lodge, in stalls prepared to the left of the tunnellike entrance. For food the animals gnawed the bark off cottonwood limbs that were thrown to them.
Black Cat, who had spent the day with Lewis and the other half of the expedition at the fort, thought it would be fine if his people at Rooptahee could see the whites perform. Lewis agreed, and the remainder of the enlisted men enjoyed their boisterous turn on January 2. 
Shortly after New Year's, the Mandans of Matootonha held a celebration of their own. The whites referred to it as the Buffalo Calling Dance. To the Indians it was the Red Stick Ceremony.  Like most Indian rituals, the Red Stick gathering was designed to fill a need, in this case the luring back of the buffalo that had wandered far away, leaving the Indians short of food.
Basically the performance was a symbolic dramatization of a myth too involved to be summarized here. First, twelve old men esteemed for their wisdom carried twelve red boards, representing buffalo, into the lodge of a man who, prompted by dreams, had volunteered to hold the ritual and provide the necessary foods. The boards were arranged like pickets in a straight line from the central fireplace to the rear wall. Criers went through the village announcing that the four-day ritual was about to begin. Old men came to the lodge and seated themselves inside, at the left of the entrance. Several young men and their wives gathered to the right.
The wives were clad only in buffalo robes draped loosely around their bodies. The idea was to lure the old men to have intercourse with them. Clark, who obtained his information from Corps members who participated in the ceremony, felt the affair had been designed by the ancient ones for their own benefit. The Indians' intent was different. They believed wisdom and power could be transmitted from old men to young through the medium of women.
After such preliminaries as feasting and smoking had been completed, one of the ancients simulated intercourse with a small doll dressed like a female. The act launched the ceremony. Each young husband said to his wife, "Help me become fortunate. Walk with my father," by which he meant an elder of a different clan from his. If the ancient one chosen by the youth was agreeable, the pair went outside, the woman clutching the elder's medicine bundle for strength. Apparently the coupling took place in the open air, in the dead of winter, with the woman's robe as a bed.
If the elder turned out to be impotent, the young people felt disgraced. The embarrassment could be remedied, but only to an extent, by a simulation of the essential act—or by choosing a substitute. The Corps's enlisted men were eagerly sought, for all whites, at that time and place, were considered to possess great wisdom, for how else could they create such wonders as guns, magnifying glasses, cloth, and shimmering blue beads? "We sent a man to this Medisen dance last night," Clark wrote on January 5, "they gave him 4 girls all this to cause the buffalow to Come near." His observation skipped a step, however. The buffalo came because the red-stick symbols, having certified the ceremony, transmitted the message to the herd: let them approach so one more necessary cycle of life could be completed, an honor to the sacrificial buffalo as well as to the people the animals saved by nourishing them.
Four days after the conclusion of the ceremony, the buffalo did indeed return. Temperatures skidded fearfully. Laroque, writing letters in a lodge in one of the Hidatsa villages, reported, "The ink freezes in my pen, though I sit so close to the fire as I can without burning my leg." The sunrise reading at Fort Mandan on January 10 was forty below.  Again a high wind roared out of the northwest, and again herds of gaunt buffalo, this time accompanied by many elk, streamed into the bottomlands.
Whites and Indians poured out for the hunt. And again there were casualties. Shortly after sunrise on the day the thermometer dropped to forty below, a Mandan boy aged about thirteen—actually he had been taken prisoner during a battle and then adopted by a Mandan family—appeared at the fort's new gate. He had been out hunting with his adoptive father the day before. Seeing how the cold was getting to the lad, the older man told him to seek the shelter of the fort. Dark caught him trudging through the snow. Breaking off some branches and scraping together some dead leaves, he lay down on them, protected only by his small buffalo robe, light leggings of antelope skin, and moccasins.
When he limped into the fort the next day, his feet were frozen. The captains thawed them in cold water, but soon it was obvious the toes could not be saved. First "they" (Lewis probably, since he was generally regarded as the camp doctor) plucked off the dead tissue. When the infection spread, they "sawed" off the members, perhaps stanching the flow of blood with a hot iron. There was no anesthetic, of course, and inasmuch as the expedition's inventory mentions no surgical saw, one doesn't like to think what sort of instrument was used. "Our captains," Ordway reported, "took the greatest care of him possible." But recovery was slow and he had to stay at the fort until February 23, when his father arrived with a sleigh to take him home. 
As a contrast: another Indian who spent the same forty-below night in the bottomlands without shelter reached the fort uninjured, prompting Clark to write, "Customs & the habits of these people has anured [them] to bare more Cold than I thought it possible for man to endure." Equally impressive, he thought, was the solicitude of the entire village for the two temporarily lost people. The boy had not been born into the tribe and the man was a person of no distinction, yet all Matootonha was anxious about their safety. 
The poor meat picked up during the January hunts, most of it lean elk fortified by an occasional thin deer, did little to replenish the Corps's larder. Fortunately the Indians' desire for ironware remained insatiable. The blacksmiths cut into four-inch squares an old sheet-iron stove the expeditions' cooks had burned out during the trip upriver, and exchanged each piece for seven or eight gallons of corn; the buyer then fashioned his acquisition into iron arrow points or hide scrapers, infinitely better than similar implements made of stone. Another fast-selling item was iron war hatchets fashioned for the buyers out of iron obtained—the journals don't say where. In any event, the Corps stayed mostly on a vegetarian diet while entertaining the first Hidatsa chiefs to visit the fort. During the same period the captains refused Laroque's request to accompany the party to the Pacific—why should a U.S. expedition help a Canadian fur company scout out the resources of the land? And, most arduously, the crew tried to chop the three boats free from ice that had encased them to the gunwales and was threatening to crush them. 
Vegetarianism did not suit for long men who were expending great amounts of energy in a bitter climate. Accordingly Clark set out on February 4 to find enough buffalo to quiet the grumblings of their stomachs. He took with him, according to Lewis, who was to attend to the journal during Clark's absence, sixteen members of the Corps and two of the Frenchmen who were living in the hut near the fort. The group traveled down the valley with their equipment in two homemade sleighs, each pulled by a horse. Overflow was loaded on a third animal. One of the horses was a gray mare followed by a young colt; another had been borrowed from Laroque's clerk, Charles McKenzie. 
Hard going. In places the river had, on occasion, thawed enough to send a sheet of water across the ice downstream. The surface had then frozen again, creating a trap of sorts. Clark broke through once, soaked his moccasins and leggings, and afterwards blistered his feet walking on ice that held him, just barely, but was rough and uneven, demanding great care to prevent slipping. During the first forty-four miles of travel the crew killed enough buffalo so that after the carcasses had been boned and the fat meat cut away from the lean, they were able to send the three horses laden with food to the fort and still keep enough to provision themselves.
On they went, pulling the sleighs by hand. Having no way to transport the meat they obtained during the rest of the journey, they put it, after butchering, into log cribs tight enough to fend off wolves, ravens, and magpies. The last cache they built was hidden in the trees near the mouth of the Heart River, where Bismarck, North Dakota, stands today. Wearily then they turned around, planning, once they reached their destination, to send a fresh party after the cached beef. On the last day, February 12, they walked thirty miles, sometimes on rippling ice and sometimes short-cutting across timbered points where the snow lay nearly knee-deep. They arrived, Clark said, "fatigued."
On the 14th, Drouillard, recently recovered from being bled and purged for pleurisy, headed downstream with the two sleighs, the three horses, and the frisky colt. Three men went with him, Robert Frazer, Silas Goodrich, and the discharged John Newman, who was working hard to be reinstated as a member of the Corps of Discovery. Toward evening, after they had traveled some two dozen miles, a hundred and six Sioux (literally) came yammering down on them. A few of the attackers cut the two horses out of the sleighs and dashed away with them. (McKenzie's would have to be paid for, adding that mite to the total cost of the expedition.) The whites grimly held onto the frightened, plunging mare. The attackers also stripped the Americans of two knives and a tomahawk, but then, apparently fearing that the whites were about to shoot, returned the tomahawk.
A strange standoff. The Americans wisely held their fire, perhaps at Drouillard's barked advice, and it was not the Indians' way to risk lives unnecessarily no matter how the odds favored them. They'd added to their reputation by taking two horses from these whites who were continually bragging about their country's power; they could count that coup dramatically for years to come. Enough! Away they raced, whooping triumphantly. Unwilling to expose themselves in a forlorn camp, the whites, the mare, and the colt trudged back through the darkness to the fort, which they reached at two in the morning.
Those damnable Sioux! Lewis sent messengers to Matootonha: come help us pursue our mutual enemy. Big White and a lesser chief responded immediately with a few men, "Some [armed] with Bows and arrows," Clark wrote, "Some with Spears & Battle axes, 2 with fuzees"—outdated muskets; hunters were out on the plains with the good guns, Big White explained. About twenty volunteers from the fort joined in. The rest stayed behind to keep an eye on the Assiniboins who were roving about the neighborhood, to gather firewood, and chip away at the icebound boats.
The only trace of the Sioux the avengers found were some cast-off moccasins, horse tracks, and the galling remnants of one of Clark's caches, which the brigands had rifled of meat and burned. But the Sioux had missed the lowest one, which Lewis found intact. Realizing at last that there was no chance of overtaking the quarry, he cooled off and turned his party to hunting. After they had bagged thirty-six deer and fourteen elk they hitched the gray mare to a sleigh loaded with six hundred pounds of meat. They piled a ton more, poor quality, winter-lean stuff, on the other, and with sixteen men pulling on its ropes, returned to Fort Mandan. They arrived about dark on February 21.
Ten days before that, the makings of one of the West's better-known legends received a major boost toward immortality, Sacagawea, Charbonneau's child-wife, went into labor. The husband was off with the hunters, and René Jessaume's spouse, aided conversationally by René, was acting as midwife. As the pains grew more excruciating (Indian women don't always drop babies as easily as buffalo drop calves), either the midwife or Jessaume offered the suggestion that powdered rattles from a rattlesnake, swallowed with water, would hurry things along. Indeed? And how did one obtain rattlesnake rattles in the dead of winter? Captain Lewis, perhaps: he was always collecting natural history specimens.
Sure enough, Lewis did have snake rattles. He handed Jessaume two "rings." Ten minutes after the dose was administered, the baby was born and given, on the father's return, perhaps the most common of French-Canadian Christian names, Jean Baptiste.  (A supposition, offered without firm evidence: what if Charbonneau, recalling the Catholic rituals of his boyhood, had asked Clark to be the infant's godfather? Would that help explain Clark's warm regard for the family and his wish to raise Jean Baptiste "as my own child"? Lewis, by contrast, considered Charbonneau of no worth except as an interpreter; Lewis was also indifferent toward the child.) 
The last days of February were marked by a run of fine weather: the sunrise temperature on the 22d was eight degrees above zero, and from then until well into March, afternoon readings were thirty-two degrees or higher. The men put their clothes and bedding out to air, and as the mercury rose, so did the pace of preparations for the coming summer.
For more than a month the crew had been struggling intermittently and fruitlessly to free the two pirogues and the keelboat from the ice. Initially the captains had feared the accumulation would crush them. The ice was three feet thick, with lenses of water caught between the layers that frustrated both chopping and picking. Later, as warming days turned the surface of the ice soggy, apprehension shifted. When the spring breakup occurred, immense floes would sweep down the river, battering the boats to pieces on their way.
Efforts redoubled, beginning February 22. Using iron-pointed levers and ropes of elk hide, the crew managed to crack both pirogues free. After smoothing out a road for log rollers, they hauled the pair ashore and up beside the pickets of the fort. The keelboat proved more stubborn. While Indians crowded about to watch, the straining workers broke the rope again and again, until at last they doubled the cord, dug in, and succeeded. 
Even before the boats had been brought ashore, the captains had revised their transportation logistics. As a result of their experiences with the shoaling Missouri the previous fall and of talks with the Indians, they decided the keelboat would be a handicap on the upper river. Consequently they determined to send it downstream. Corporal Richard Warfington's soldiers, who had wrestled the white pirogue upstream, would act as crew and fight off the Sioux if that proved necessary. Those of the red pirogue's erstwhile French boatmen who remained in the vicinity would go along as passengers, as would the discharged and disgraced Reed and Newman; though Lewis recognized Newman's efforts at rehabilitation, he sternly refused to reinstate him. The returning craft would also carry two dozen crates of specimens and a bundle of reports for Jefferson.
The two pirogues, both more maneuverable and of shallower draft than the keelboat, would be used for completing the ascent of the Missouri. They were not roomy enough, however, to hold the thirty-three persons and the one dog of what would become known as the permanent party, plus, of course, their baggage. At the end of the month, accordingly, part of the fort's garrison was sent upstream to find cottonwood trees big enough for making dugouts—six long, narrow affairs, unstable but capable of being sailed when the wind was right. The trees the scouts found were awkwardly located some six miles up the Missouri and another mile and a half from its banks.  Carrying the finished dugouts to the stream would be difficult, but no matter. Pushing to the Pacific was the consuming thought right then.
Concurrently with the tree hunters' departure, Joseph Gravelines, two Frenchmen, and two Arikara Indians arrived at the fort. From them Lewis and Clark learned, with renewed anger, that the Sioux who had attacked Drouillard and his meat gatherers two weeks earlier—one hundred and six of them by Gravelines's count—had stopped at the Arikara towns on their way downstream and had boasted of their deeds. This annoyed the Rees, as the Arikaras were often called, who were out of sorts with the Sioux, anyway. For stories had reached the river Indians that Murdock Cameron a British trader on the St. Peter's, was selling guns to the belligerent tribe. Cameron had supposed the buyers would use the weapons against their old enemy, the Chippewa, who had recently killed three of his men. But the feeling of power brought by the guns had led several bands of the Sioux to vow an attack on the Arikaras for entering into an alliance with the Mandans. During the battling the Corps of Discovery was to be annihilated for engineering the disruption. Only Black Buffalo, who had helped restrain the Bois Brulé Tetons during the September confrontation with the explorers, was refusing to join the projected assault. 
This information was counterbalanced, in the captains' estimation, by a letter from Antoine Tabeau that Gravelines delivered. Frightened by the Sioux threat, the trader wrote, the Arikaras wanted to cement their tentative alliance with the Mandans and Hidatsas by moving north to live close to the upper river Indians. Would the Mandans and Hidatsas be agreeable?
Delighted, Lewis and Clark conveyed the message to both tribes. With some reserve the Mandan and Hidatsa chiefs suggested that a proper Arikara delegation be sent up the Missouri to talk things over. Still, it looked as though the Grand Plan for breaking the Sioux's grip on the river was going to work. Using the Frenchmen who had arrived with Gravelines as couriers, the captains sent a letter back to Tabeau, urging him to press for the conference. As for Gravelines, he stayed at Fort Mandan. The captains, who considered the trader to be, in Lewis's words, "an honest discrete man and an excellent boat-man," had hired him to pilot the keelboat down the Missouri, picking up as many Arikara chiefs along the way as would consent to come aboard. He would also collect whatever Yankton Sioux, Omahas, Otos, and Missouri Pierre Dorion had managed to gather during the winter. (No Mandans or Hidatsas would agree to join the excursion for fear of the Tetons.) After landing in St. Louis, Gravelines would help escort the red dignitaries to Washington.
Washington! Although Lewis and Clark's thoughts kept veering toward the Pacific, they could not leave until they had finished putting into orderly shape for Jefferson's eyes the staggering number of specimens, maps, and detailed reports they had been working over since their departure from Camp Wood ten months before.
They had collected enough objects to equip a small museum—sixty-seven specimens of soil, salts, and minerals; sixty examples of plants, including one supposed to be a sovereign remedy for the bites of rattlesnakes and rabid wolves; the hides of many animals, some stuffed and several unknown to Americans of the time; four live magpies, a live sharp-tailed grouse, and a live prairie dog, probably the one they had driven from its burrow farther downstream with kegs of water; a variety of embalmed insects; and many Indian curiosities. All this had to be annotated, packaged, and labeled. 
The annotations were essentially rewritten field notes about materials collected under severe limitation. Neither man was a trained scientist. Lewis's crash courses prior to his departure from Washington had taught him how to focus his inquiries in different disciplines, but not much else. Both, however, were conscientious observers, each with a particular talent. Clark was more adept at eliciting information from Indians and at illustrating his written descriptions with rough-hewn but accurate drawings. Lewis had an unusually sharp eye for the details of flora and fauna, and a trenchant pen for conveying the essence of his studies.
To the physical objects they sent downstream on the keelboat they added voluminous reports on the climate, topography, river drainage systems, soil fertility, and Indian cultures of all Upper Louisiana Territory. Because they had been locked inside the Missouri River trench, except for climbs to occasional viewpoints, they'd had to extend their observations by questioning Indians through interpreters and by interviewing such knowledgeable traders as Antoine Tabeau and Hugh Heney of the North West Company, the latter of whom had joined Laroque at the Hidatsa villages in December.
The geographic material they had collected they organized into two documents with similar titles. One, a discourse prepared by Lewis, described the streams that discharged into the Missouri—their length, navigability, sources, and the appearance of the lands through which they flowed. He called his compilation "A Summary View of Rivers and Creeks." Clark supplemented that essay with four arithmetic tables that gave the distances from one stream mouth to the next one upstream, an estimate of each tributary's length, and a record of latitudes taken here and there by the captains during the upriver journey. He called these tables "A Summary View of Rivers, Creeks, and Remarkable Places," the last term referring, in the main, to large islands and the site of both deserted and occupied Indian villages. Both summaries ended with guesswork, based on Indian information, about the country that lay west of the Missouri. 
Their data on the territory's native inhabitants were contained in what Lewis and Clark entitled "Estimate of Eastern Indians," eastern because it dealt with tribes living on the inland side of the Continental Divide. When including the "Estimate" in a special message to Congress on February 19, 1806, Jefferson retitled it "A Statistical View of the Indian Nations Inhabiting the Territory of Louisiana and the Countries Adjacent to its Northern and Western Boundaries." The "Estimate," like the "Summaries," was based largely on hearsay, as the captains frankly admitted. Even so, it contained more information about Upper Louisiana than anyone else in the United States could muster, and it would give would-be traders a basis for planning.
The last point was important. Although Jefferson had told Lewis to hunt out knowledge for its own sake, the president had not overlooked pragmatic goals. The dichotomy is clearly revealed in the captains' handling of Indian studies. Before leaving Washington, Lewis had been advised to collect information about such things as Indian pulse rates, menstrual cycles, funeral customs, medical practices, and religious observances. At the same time he was to record anything that might be helpful in establishing and maintaining commercial contacts. Quickly realizing the impossibility of ferreting out extensive anthropological detail during the limited time they could spend with most tribes, Lewis and Clark had concentrated their search on matters that would primarily interest traders—language, the home territories of the different tribes, the peoples with whom they were at peace or war, the potential value of their commerce, and, for the government, the possibility of relocating important tribes near federal trading posts in the event the Indian Bureau decided such interference with private enterprise was advisable.
For example, consider the Hidatsas, who were called Minitaris in the "Estimate." According to Lewis and Clark, the tribe often left their domed houses to range along both banks of the Missouri up to and beyond the mouth of the Yellowstone. The area abounded in beaver. The Hidatsas did not hunt the valuable fur-bearing animals, however, because the chase was difficult and they could get the supplies they needed by bartering horses and vegetables with the Assiniboins, Crows, Cheyennes—and from the Canadians. Private traders would like to know such things. And the government would like to know that the Hidatsas probably could be prevailed on to relocate their villages near the mouth of the Yellowstone if a federal trading post were established there. Such a move might be necessary, for Lewis and Clark had heard, through Charbonneau, rumors to the effect that the North West Company was planning to build a post at the mouth of the Knife.
And the Sioux. Their many bands, named and located in the "Estimate," roamed a huge area. Of these bands the Tetons were "the vilest miscreants of the savage race," a remark that overlooked Black Buffalo's perhaps temporary coolness toward joining the projected war against the Mandans and the Americans. The Tetons' trade, the captains said, might be of value if those Indians were reduced to order by armed intervention. And that, too, was something every trader in St. Louis would read with interest. An inevitable question arises: How did Lewis and Clark themselves evaluate this territorial acquisition about which they had written so much? In his journal Clark had noted such unfavorable factors as growing alkalinity in certain creeks and bordering ground. Both had read in the diaries of their predecessors' remarks about sterility and semiaridity. They had experienced the harsh, desiccating winds that blew almost constantly across the High Plains. They had endured the crushing cold of a plains winter. But were they pessimistic about the area's adaptability to white settlement? The answer has to be a firm negative.
A recurrent phrase in Clark's upriver journal is "butifull prospect," which is not a term he would have applied to views that struck him as unfavorable to human occupation. Lewis is more specific. In a letter he wrote his mother just before leaving Fort Mandan, he grows almost ecstatic.  The Missouri, "so far as we have yet ascended, waters one of the fairest portions of the globe." He had heard the area was "barren, steril, and sandy." Not so. A fertile soil of loam sustained a luxuriant growth of grass on which game abounded. The only lack was timber, and that was not the result of adverse climate or inadequate soil, but of raging grass fires the Indians kindled either carelessly at their camps or set deliberately, partly for excitement and partly to control the movement of game. For that matter, the Corps had started some towering blazes, too, to attract the attention of tribes they wanted to contact, a matter the letter did not mention.
(Lewis's challenging remark about the treeless nature of the plains, incidentally, has stout defenders. In spite of relatively light precipitation trees can be grown there, as many a farmer has discovered. The Nebraska National Forest in the western sandhills of that state, which was planted as a calculated experiment flourished as soon as grass fires were controlled.  No major lumber company has sought to exploit the area, however.)
At this late date it is hard to know to what extent Lewis saw the plains through preconditioned eyes. The American West was supposed to be fertile. America's advancing frontier, and hence a great part of the young nation's strength, depended on that axiom.  Jefferson knew of the treeless expanses in the continent's interior, but, less aware than Lewis of fire's ravages, he suggested that the soil out there was not too poor, but too rich for trees, thus turning the average pioneer's conventional wisdom upside down. Both Meriwether Lewis and William Clark, children of agriculturists, had absorbed the faith of an expansive agrarian society without question. The multitudes of grass-eating animals the Corps subsisted on proved that nutritious growth existed, and the herds were said to become more numerous as one pressed on west from the Mandan-Hidatsa villages—settlements which were, after all, based on agriculture. Though the captains had not yet laid eyes on the valley of the Yellowstone River, it, too, was reputed to be another terrestrial paradise. Why doubt? The best was yet to be.
The key that locked these data together was a map of a highly conjectural West that Clark drew during the long nights at Fort Mandan. Its base was the King-Arrowsmith chart he had studied at Camp Wood when first estimating distances and potential routes to the Pacific. On that foundation he superimposed such new information and corrections as Lewis and he had gleaned from talks with Indians and with every trader they had met during their upstream journey.
First, Clark filled in the largely blank areas between the upper Mississippi and the Missouri, drawing his facts from Hugh Heney, once a partner of Regis Loisel's but more recently an employee of the North West Company of Canada. That done, Clark turned his attention to the lower and middle Missouri's major tributaries—the Osage, Kansas, Platte, Niobrara, and Cheyenne rivers. In all cases he showed the streams heading too far west. Most were represented as rising in the Black Hills of present South Dakota, a range that Clark showed as extending much farther north and south than is the case. Contributing to his errors was Lewis's miscalculation of the longitude of the Mandan villages—99°24'45". The correct position is 101°27'. David Thompson of the North West company had been roughly ninety miles closer to the truth half a dozen years earlier, although the captains, convinced of the superiority of their methods, boasted to Laroque that they had corrected his colleague's figures. 
Lewis and Clark's primary challenge, of course, was learning as much as possible about the country they—and after them the pioneer merchants of the United States—would need to know in order to reach the Orient-facing harbors of the Pacific Coast. In this instance their informants were the Mandans and Hidatsas. Fortunately the early hostility of the latter tribe thawed; for the Hidatsas, the captors of Sacagawea, were accustomed to range as far west as the Continental Divide during their horse-stealing raids against the Snake Indians. There is no evidence, incidentally, that the young Snake woman, Sacagawea, contributed in any way to the production of the map.
The obstacles to accurate mapping were prodigious.  The Indians had no compasses. They indicated directions by pointing more or less along the lines followed by the sun at different seasons of the year. This resulted in a certain fuzziness for a geographer hoping to move from one distant point to another along a zigzagging course. The Indians, moreover, did not measure distances in miles, but in "sleeps" or "suns." The ground they covered during one "sun" depended on the pace of their horses. The Corps, however, hoped to journey as far as the Missouri's headwaters by boat. Correlating the two standards was tentatively done, to say the least. In addition, the Indians had scant notions of navigability, so that their descriptions of streams as they appeared to a man on horseback were hardly definitive for boats. Plus this: on their war excursions against the Snakes, the Hidatsas avoided the rough breaks south of the Missouri and struck directly across the plains. As a result they had not even seen the river for long distances. Finally, there were the usual frustrations of grasping information that passed through several mouths—a Hidatsa warrior to Charbonneau, Charbonneau to Drouillard or Cruzatte, and thence to the interrogator.
The Indians could draw rough maps, however, either on hide or on smoothed patches of earth, using an awl or a twig to scratch out river courses and adding little heaps of sand to indicate mountains. Directions as well as topography emerged with fair accuracy on such charts (if communication came through accurately), but distances remained elusive. Perhaps the best way to show the differences between what the captains anticipated and what they found will be to outline the expectations portrayed on the map and then let reality emerge in the narrative as it progresses.
First, the Yellowstone River . Lewis and Clark had picked up glimmerings of the stream from the journals and cartographic speculations of their predecessors, Jean Baptiste Truteau, James Mackay, and John Evans. During their talks with the Mandan chief Big White and with various Hidatsas, the Yellowstone and its major tributaries, such as the Bighorn, emerged with fair correctness. But somehow they got the notion that the river rose in the Rockies near the spot where "the Spaniards reside." Hardly, especially when one considers the nature of the lofty peaks that intervene between the Yellowstone's farthest headwaters and those of the "Spanish" streams, presumably the Platte, Rio Grande, and Colorado. However, awareness of the Yellowstone did enable the captains to get rid of the Lesser Missisourie of the King-Arrowsmith chart (it became today's relatively insignificant Little Missouri), and with that out of the way they were able to accommodate a main Missouri bending far to the south in western Montana.
They also visualized the Yellowstone as boiling down out of rough, heavily timbered country into "one of the fairest portions of Louisiana, a country not yet hunted and abounding in animals of the fur kind." Now, that was information that would cause a stir in St. Louis. (It also stirred young François Laroque, who, after being denied permission to accompany the Corps to the Pacific, set out with a party of Crow Indians to look over the Yellowstone region for the North West Company. On the trip Laroque did hear of the Great Falls of the Yellowstone, but he did not reach as high as today's Yellowstone National Park.) Inasmuch as Jefferson had advised Lewis to keep an eye on the Missouri southern tributaries—he had been thinking of ways to reach Spanish New Mexico —Lewis promised him, when writing in April 1806, that the Corps would explore the Yellowstone on its return from the Pacific. This is significant, for it shows they had already learned that a short trip east from Three Forks over what is now Bozeman Pass would bring them into the lovely valleys of the upper Yellowstone near today's Livingston. Fur traders would relish that knowledge, too. 
The White Earth River . The stream, its name a translation of the Indian Ok-hah, Ah-zhah , was said to debouch into the Missouri from the north, three miles below and opposite to the mouth of the Yellowstone. Supposedly the source of the White Earth lay far to the north, near the south fork of the Saskatchewan. If so and if Louisiana Territory was held to embrace every tributary of the Missouri, this would thrust a barrier across Canadian expansion to the west and, as Lewis wrote triumphantly, would give American fur traders a good run at the fabled beaver regions of Athabasca.
The Milk River . The Indians called it Ah-mah-tah, ru-shush-sher , or "The River that Scolds at All Others." Lewis and Clark believed that it, too, might give access to the Saskatchewan. According to their understanding of Indian information, it was the last major northern tributary of the Missouri. Encountering it would mean they were well on their way to the thunderous Great Falls of the Missouri, a natural phenomenon that both awed and fascinated their Indian informants.
The Great Falls . The roar of this "most tremendious cataract" reputedly could be heard for miles. The river rushed so fast, Lewis reported in his "Summary View of Rivers and Creeks," that on reaching the brink of the precipice it shot out so far that there was space, at the bottom, "for several persons to pass abrest underneath the torrent, from bank to bank, without wetting their feet." Passing around the cataract was no problem. A half-mile portage along the level plain on the north side of the river would bring the Corps to the spot where the Missouri "assumes it's usual appearance, being perfectle navigable."
The Sun River . The Indians called this stream the Medicine. It enters the Missouri from the west, and according to the Indians (insofar as the captains understood them) it rose in the Rocky Mountains opposite to a west-flowing stream that presumably was a tributary of the Columbia. But the Medicine was reported to be too swift and shallow to be navigated. Besides, the captains had been ordered to explore the Missouri to its headwaters. Accordingly they spent little time trying to unravel the confusing details that clustered around the natives' descriptions of the small stream.
Three Forks . Before the captains reached the Great Falls they would notice that the trough of the Missouri bent from its westward course to the southwest. It would maintain that direction through several parallel ridges. A little more than a hundred miles beyond the Great Falls, as the explorers computed the distance, the stream would divide into three forks. The western one would lead to a fifteen-mile portage across the Continental Divide.
The Continental Divide looked on Clark's map much as it looked on the King-Arrowsmith—the westernmost of four north-south ridges that rose rather mildly out of gentle valleys or perhaps out of a slightly elevated plain. Clark even retained the mythological names of some of the divide's peaks—the King, the Heart, and so on. The western base of this easily crossed divide, the Indians asserted, was washed by a large river that ran from south to north. Farther than that the Hidatsas had never been. The captains were confident, however, that this river was the hypothecated south fork of the Columbia. After flowing through plains almost as level as those bordering most of the Missouri, the fork would enter the main Columbia. The journey from the divide to the Pacific should be little more than three hundred miles. With that notion firmly in mind, Lewis assured Jefferson that the Corps could easily reach the ocean and return to the headwaters of the Missouri or perhaps even to the Mandan towns before winter set in. 
By March 20, 1805, the six pirogues designed to take the place of the keelboat had been completed. Clark took enough men upstream to lug the new craft a mile and a half to the river and then float them amid chunks of broken ice to the fort, where they were carefully caulked. During their labors the explorers were amazed by a kind of Indian hunting totally new to them. Buffalo trying to cross the stream at breakup time were often marooned on big cakes of floating ice. Seeing one approach, a hunter or two would take off to intercept it, jumping dexterously from floe to floe until they reached the cake the buffalo occupied. Rendered harmless by its insecure footing, the shaggy beast received its death wound almost without a struggle. The hunters then paddled the icy hearse ashore.
Charles McKenzie's journal supplies an additional item. During the winter many buffalo had died upstream. They, too, floated down, on the floes or among them. Young Indians skipped from cake to cake with ropes to haul the nauseating creatures ashore, for when "the flesh is a greenish hue ... and so ripe, so tender, that very little boiling is necessary—the stench is intolerable—yet the soup they make from it . . . is reckoned delicious." 
By April 6 the river was clear of ice, and the boats were ready to start both upstream and down to their separate destinations. The men, Lewis wrote, were "in good health [except for the usual venereal complaints] and excellent sperits, zealously attached to the enterprise, and anxious to proceed."  But there was a last-minute delay. A messenger crossed the river, probably in an Indian bullboat, and reported that the entire Arikara nation, or so the captains understood, was coming north to build new towns nearby.
Promptly Lewis and Clark dispatched an interpreter over to meet the throng. It turned out there were ten Arikaras, the delegation the Mandans and Hidatsas had requested to come upstream to smoke in amity while discussing the proposed relocation of the Arikara towns. The interpreter also passed on a letter from Tabeau that stated that three Sioux chiefs (probably not Tetons) and some Arikaras had listened to his blandishments and would board the keelboat when it passed the villages on its way to St. Louis. Tabeau asked permission to join the party with four hands and three thousand pounds of fur. 
Good omens. The captains' diplomacy was showing firm signs of moving ahead, and the keelboat would be well protected if any band of truculent Sioux tried to interfere. In high spirits the little fleet of two pirogues and six small "canoes" pushed off at 4:00 p.m. on April 7. Lewis, who by then was definitely keeping a journal, eyed the procession proudly. "This little fleet altho' not quite so rispectable as those of Columbus or Capt. Cook, were still viewed by us with as much pleasure as those deservedly famous adventurers beheld their's." Clark, less given to introspection, used his journal to call the roll of those aboard (not counting himself and Lewis): Sergeants Nathaniel Pryor, John Ordway, and Patrick Gass. Privates William Bratton. John Collins, John Colter, Pierre Cruzatte. Joseph Field, Reuben Field, Robert Frazer, George Gibson, Silas Goodrich. Hugh Hall, Thomas Howard, François Labiche, Baptiste Lepage, Hugh McNeal, John Potts, George Shannon, John Shields, John Thompson, William Werner, Joseph Whitehouse, Alexander Willard. Richard Windsor, Peter Wiser. Interpreters George Drouillard and Toussaint Charbonneau. York, Sacagawea, and her two-month-old infant, Baptiste. And Clark should have added the dog Seaman, who ate as much as any one of the men.
A mixed bag and far to go. But by that time all who were capable of looking ahead had been thoroughly tested both individually and as a unit, except for Charbonneau and Lepage, both added at Fort Mandan. Probably the others would have echoed Lewis's statement to Jefferson, "With such men I have every thing to hope and but little to fear." Most of the crew (there's no telling about Sacagawea) might even have agreed with Lewis's statement in his journal, "I could but esteem this moment of departure among the most happy of my life," though whether or not they would return "was for experiment yet to determine."