The story of the United States is that of a series of frontiers which the hand of man has reclaimed from nature and the savage, and which courage and foresight have gradually transformed from desert waste to virile commonwealth. It is the story of one long struggle, fought over different lands and by different generations, yet ever repeating the conditions and episodes of the last period in the next. The winning of the first frontier established in America its first white settlements. Later struggles added the frontiers of the Alleghanies and the Ohio, of the Mississippi and the Missouri. The winning of the last frontier completed the conquest of the continent.

The greatest of American problems has been the problem of the West. For four centuries after the discovery there existed here vast areas of fertile lands which beckoned to the colonist and invited him to migration. On the boundary between the settlements and the wilderness stretched an indefinite line that advanced westward from year to year. Hardy pioneers were ever to be found ahead of it, blazing the trails and clearing in the valleys. The advance line of the farmsteads was never far behind it. And out of this shifting frontier between man and nature have come the problems that have occupied and directed American governments since their beginning, as well as the men who have solved them. The portion of the population residing in the frontier has always been insignificant in number, yet it has well-nigh controlled the nation. The dominant problems in politics and morals, in economic development and social organization, have in most instances originated near the frontier or been precipitated by some shifting of the frontier interest.

The controlling influence of the frontier in shaping American problems has been possible because of the construction of civilized governments in a new area, unhampered by institutions of the past or conservative prejudices of the present. Each commonwealth has built from the foundation. An institution, to exist, has had to justify itself again and again. No force of tradition has kept the outlawed fact alive. The settled lands behind have in each generation been forced to remodel their older selves upon the newer growths beyond.

Individuals as well as problems have emerged from the line of the frontier as it has advanced across a continent. In the conflict with the wilderness, birth, education, wealth, and social standing have counted for little in comparison with strength, vigor, and aggressive courage. The life there has always been hard, killing off the weaklings or driving them back to the settlements, and leaving as a result a picked population not noteworthy for its culture or its refinements, but eminent in qualities of positive force for good or bad. The bad man has been quite as typical of the frontier as the hero, but both have possessed its dominant virtues of self-confidence, vigor, and initiative. Thus it has been that the men of the frontiers have exerted an influence upon national affairs far out of proportion to their strength in numbers.

The influence of the frontier has been the strongest single factor in American history, exerting its power from the first days of the earliest settlements down to the last years of the nineteenth century, when the frontier left the map. No other force has been continuous in its influence throughout four centuries. Men still live whose characters have developed under its pressure. The colonists of New England were not too early for its shaping.

The earliest American frontier was in fact a European frontier, separated by an ocean from the life at home and meeting a wilderness in every extension. English commercial interests, stimulated by the successes of Spain and Portugal, began the organization of corporations and the planting of trading depots before the sixteenth century ended. The accident that the Atlantic seaboard had no exploitable products at once made the American commercial trading company of little profit and translated its depots into resident colonies. The first instalments of colonists had little intention to turn pioneer, but when religious and political quarrels in the mother country made merry England a melancholy place for Puritans, a motive was born which produced a generation of voluntary frontiersmen. Their scattered outposts made a line of contact between England and the American wilderness which by 1700 extended along the Atlantic from Maine to Carolina. Until the middle of the eighteenth century the frontier kept within striking distance of the sea. Its course of advance was then, as always, determined by nature and geographic fact. Pioneers followed the line of least resistance. The river valley was the natural communicating link, since along its waters the vessel could be advanced, while along its banks rough trails could most easily develop into highways. The extent and distribution of this colonial frontier was determined by the contour of the seaboard along which it lay.

Running into the sea, with courses nearly parallel, the Atlantic rivers kept the colonies separated. Each colony met its own problems in its own way. England was quite as accessible as some of the neighboring colonies. No natural routes invited communication among the settlements, and an English policy deliberately discouraged attempts on the part of man to bring the colonies together. Hence it was that the various settlements developed as island frontiers, touching the river mouths, not advancing much along the shore line, but penetrating into the country as far as the rivers themselves offered easy access.

For varying distances, all the important rivers of the seaboard are navigable; but all are broken by falls at the points where they emerge upon the level plains of the coast from the hilly courses of the foothills of the Appalachians. Connecting these various waterfalls a line can be drawn roughly parallel to the coast and marking at once the western limit of the earliest colonies and the line of the second frontier. The first frontier was the seacoast itself. The second was reached at the falls line shortly after 1700.

Within these island colonies of the first frontier American life began. English institutions were transplanted in the new soil and shaped in growth by the quality of their nourishment. They came to meet the needs of their dependent populations, but they ceased to be English in the process. The facts of similarity among the institutions of Massachusetts and Pennsylvania, or Virginia, or Georgia, point clearly to the similar stocks of ideas imported with the colonists, and the similar problems attending upon the winning of the first frontier. Already, before the next frontier at the falls line had been reached, the older settlements had begun to develop a spirit of conservatism plainly different from the attitude of the old frontier. The falls line was passed long before the colonial period came to an end, and pioneers were working their way from clearing to clearing, up into the mountains, by the early eighteenth century. As they approached the summit of the eastern divide, leaving the falls behind, the essential isolation of the provinces began to weaken under the combined forces of geographic influence and common need. The valley routes of communication which determined the lines of advance run parallel, across the first frontier, but have a tendency to converge among the mountains and to stand on common ground at the summit. Every reader of Francis Parkman knows how in the years from 1745 to 1756 the pioneers of the more aggressive colonies crossed the Alleghanies and meeting on the summit found that there they must make common cause against the French, or recede. The gateways of the West converge where the headwaters of the Tennessee and Cumberland and Ohio approach the Potomac and its neighbors. There the colonists first came to have common associations and common problems. Thus it was that the years in which the frontier line reached the forks of the Ohio were filled with talk of colonial union along the seaboard. The frontier problem was already influencing the life of the East and impelling a closer union than had been known before.

The line of the frontier was generally parallel to the coast in 1700. By 1800 it had assumed the form of a wedge, with its apex advancing down the rivers of the Mississippi Valley and its sides sloping backward to north and south. The French war of 1756–1763 saw the apex at the forks of the Ohio. In the seventies it started down the Cumberland as pioneers filled up the valleys of eastern Kentucky and Tennessee. North and south the advance was slower. No other river valleys could aid as did the Ohio, Cumberland, and Tennessee, and population must always follow the line of least resistance. On both sides of the main advance, powerful Indian confederacies contested the ground, opposing the entry of the whites. The centres of Indian strength were along the Lakes and north of the Gulf. Intermediate was the strip of "dark and bloody ground," fought over and hunted over by all, but occupied by none; and inviting white approach through the three valleys that opened it to the Atlantic.

The war for independence occurred just as the extreme frontier started down the western rivers. Campaigns inspired by the West and directed by its leaders saw to it that when the independence was achieved the boundary of the United States should not be where England had placed it in 1763, on the summit of the Alleghanies, but at the Mississippi itself, at which the lines of settlement were shortly to arrive. The new nation felt the influence of this frontier in the very negotiations which made it free. The development of its policies and its parties felt the frontier pressure from the start. Steadily after 1789 the wedge-shaped frontier advanced. New states appeared in Kentucky and Tennessee as concrete evidences of its advance, while before the century ended, the campaign of Mad Anthony Wayne at the Fallen Timbers had allowed the northern flank of the wedge to cross Ohio and include Detroit. At the turn of the century Ohio entered the Union in 1803, filled with a population tempted to meet the trying experiences of the frontier by the call of lands easier to till than those in New England, from which it came. The old eastern communities still retained the traditions of colonial isolation; but across the mountains there was none of this. Here state lines were artificial and convenient, not representing facts of barrier or interest. The emigrants from varying sources passed over single routes, through single gateways, into a valley which knew little of itself as state but was deeply impressed with its national bearings. A second war with England gave voice to this newer nationality of the newer states.

The war with England in its immediate consequences was a bad investment. It ended with the government nearly bankrupt, its military reputation redeemed only by a victory fought after the peace was signed, its naval strength crushed after heroic resistance. The eastern population, whose war had been forced upon it by the West, was bankrupt too. And by 1814 began the Hegira. For five years the immediate result of the struggle was a suffering East. A new state for every year was the western accompaniment.

The westward movement has been continuous in America since the beginning. Bad roads, dense forests, and Indian obstructers have never succeeded in stifling the call of the West. A steady procession of pioneers has marched up the slopes of the Appalachians, across the trails of the summits, and down the various approaches to the Mississippi Valley. When times have been hard in the East, the stream has swollen to flood proportions. In the five years which followed the English war the accelerated current moved more rapidly than ever before; while never since has its speed been equalled save in the years following similar catastrophes, as the panics of 1837 and 1857, or in the years under the direct inspiration of the gold fields.

Five new states between 1815 and 1821 carried the area of settlement down the Ohio to the Mississippi, and even up the Missouri to its junction with the Kansas. The whole eastern side was filled with states, well populated along the rivers, but sparsely settled to north and south. The frontier wedge, noticeable by 1776, was even more apparent, now that the apex had crossed the Mississippi and ascended the Missouri to its bend, while the wings dragged back, just including New Orleans at the south, and hardly touching Detroit at the north. The river valleys controlled the distribution of population, and as yet it was easier and simpler to follow the valleys farther west than to strike out across country for lands nearer home but lacking the convenience of the natural route.

For the pioneer advancing westward the route lay direct from the summit of the Alleghanies to the bend of the Missouri. The course of the Ohio facilitated his advance, while the Missouri River, for two hundred and fifty miles above its mouth, runs so nearly east and west as to afford a natural continuation of the route. But at the mouth of the Kansas the Missouri bends. Its course changes to north and south and it ceases to be a highway for the western traveller. Beyond the bend an overland journey must commence. The Platte and Kansas and Arkansas all continue the general direction, but none is easily navigable. The emigrant must leave the boat near the bend of the Missouri and proceed by foot or wagon if he desire to continue westward. With the admission of Missouri in 1821 the apex of the frontier had touched the great bend of the river, beyond which it could not advance with continued ease. Population followed still the line of easiest access, but now it was simpler to condense the settlements farther east, or to broaden out to north or south, than to go farther west. The flanks of the wedge began to move. The southwest cotton states received their influx of population. The country around the northern lakes began to fill up. The opening of the Erie Canal in 1825 made easier the advancing of the northern frontier line, with Michigan, Wisconsin, and even Iowa and Minnesota to be colonized. And while these flanks were filling out, the apex remained at the bend of the Missouri, whither it had arrived in 1821.

There was more to hold the frontier line at the bend of the Missouri than the ending of the water route. In those very months when pioneers were clearing plots near the mouth of the Kaw, or Kansas, a major of the United States army was collecting data upon which to build a tradition of a great American desert; while the Indian difficulty, steadily increasing as the line of contact between the races grew longer, acted as a vigorous deterrent.

Schoolboys of the thirties, forties, and fifties were told that from the bend of the Missouri to the Stony Mountains stretched an American desert. The makers of their geography books drew the desert upon their maps, coloring its brown with the speckled aspect that connotes Sahara or Arabia, with camels, oases, and sand dunes. The legend was founded upon the fact that rainfall becomes more scanty as the slopes approach the Rockies, and upon the observation of Major Stephen H. Long, who traversed the country in 1819–1820. Long reported that it could never support an agricultural population. The standard weekly journal of the day thought of it as "covered with sand, gravel, pebbles, etc." A writer in the forties told of its "utter destitution of timber, the sterility of its sandy soil," and believed that at "this point the Creator seems to have said to the tribes of emigration that are annually rolling toward the west, 'Thus far shalt thou go, and no farther.'" Thus it came about that the frontier remained fixed for many years near the bend of the Missouri. Difficulty of route, danger from Indians, and a great and erroneous belief in the existence of a sandy desert, all served to barricade the way. The flanks advanced across the states of the old Northwest, and into Louisiana and Arkansas, but the western outpost remained for half a century at the point which it had reached in the days of Stephen Long and the admission of Missouri.

By 1821 many frontiers had been created and crossed in the westward march; the seaboard, the falls line, the crest of the Alleghanies, the Ohio Valley, the Mississippi and the Missouri, had been passed in turn. Until this last frontier at the bend of the Missouri had been reached nothing had ever checked the steady progress. But at this point the nature of the advance changed. The obstacles of the American desert and the Rockies refused to yield to the "heel-and-toe" methods which had been successful in the past. The slavery quarrel, the Mexican War, even the Civil War, came and passed with the area beyond this frontier scarcely changed. It had been crossed and recrossed; new centres of life had grown up beyond it on the Pacific coast; Texas had acquired an identity and a population; but the so-called desert with its doubtful soils, its lack of easy highways and its Indian inhabitants, threatened to become a constant quantity.

From 1821 to 1885 extends, in one form or another, the struggle for the last frontier. The imperative demands from the frontier are heard continually throughout the period, its leaders in long succession are filling the high places in national affairs, but the problem remains in its same territorial location. Connected with its phases appear the questions of the middle of the century. The destiny of the Indian tribes is suggested by the long line of contact and the impossibility of maintaining a savage and a civilized life together and at once. A call from the farther West leads to more thorough exploration of the lands beyond the great frontier, bringing into existence the continental trails, producing problems of long-distance government, and intensifying the troubles of the Indians. The final struggle for the control of the desert and the elimination of the frontier draws out the tracks of the Pacific railways, changes and reshapes the Indian policies again, and brings into existence, at the end of the period, the great West. But the struggle is one of half a century, repeating the events of all the earlier struggles, and ever more bitter as it is larger and more difficult. It summons the aid of the nation, as such, before it is concluded, but when it is ended the first era in American history has been closed.