The other Western States still kept touch on the old colonial communities of the sea-coast, having a second or alternative outlet through Louisiana, newly acquired by the United States, it is true, but which was nevertheless an old settled land. Missouri, however, had lost all connection with the sea-coast, and though, through her great river towns, swarming with raftsmen and flat-boatmen, she drove her main and most thriving trade with the other Mississippi cities, yet her restless and adventure-loving citizens were already seeking other outlets for their activity, and were establishing trade relations with the Mexicans; being thus the earliest among our people to come into active contact with the Hispano-Indian race from whom we afterwards wrested so large a part of their inheritance. Missouri was thrust out beyond the Mississippi into the vast plains-country of the Far West, and except on the river-front was completely isolated, being flanked on every side by great stretches of level wilderness, inhabited by roaming tribes of warlike Indians. Thus for the first time the borderers began to number in their ranks plainsmen as well as backwoodsmen. In such a community there were sure to be numbers of men anxious to take part in any enterprise that united the chance of great pecuniary gain with the certainty of even greater personal risk, and both these conditions were fulfilled in the trading expeditions pushed out from Missouri across the trackless wastes lying between it and the fringe of Mexican settlements on the Rio del Norte. The route followed by these caravans, which brought back furs and precious metals, soon became famous under the name of the Santa Fé trail; and the story of the perils, hardships, and gains of the adventurous traders who followed it would make one of the most striking chapters of American history.
Among such people Benton's views and habits of thought became more markedly Western and ultra-American than ever, especially in regard to our encroachments upon the territory of neighboring powers. The general feeling in the West upon this last subject afterwards crystallized into what became known as the "Manifest Destiny" idea, which, reduced to its simplest terms, was: that it was our manifest destiny to swallow up the land of all adjoining nations who were too weak to withstand us; a theory that forthwith obtained immense popularity among all statesmen of easy international morality. It cannot be too often repeated that no one can understand even the domestic, and more especially the foreign, policy of Benton and his school without first understanding the surroundings amidst which they had been brought up and the people whose chosen representatives they were. Recent historians, for instance, always speak as if our grasping after territory in the Southwest was due solely to the desire of the Southerners to acquire lands out of which to carve new slave-holding states, and as if it was merely a move in the interests of the slave-power. This is true enough so far as the motives of Calhoun, Tyler, and the other public leaders of the Gulf and southern sea-board states were concerned. But the hearty Western support given to the movement was due to entirely different causes, the chief among them being the fact that the Westerners honestly believed themselves to be indeed created the heirs of the earth, or at least of so much of it as was known by the name of North America, and were prepared to struggle stoutly for the immediate possession of their heritage.
One of Benton's earliest public utterances was in regard to a matter which precisely illustrates this feeling. It was while Missouri was still a territory, and when Benton, then a prominent member of the St. Louis bar, had by his force, capacity, and power as a public speaker already become well known among his future constituents. The treaty with Spain, by which we secured Florida, was then before the Senate, which body had to consider it several times, owing to the dull irresolution and sloth of the Spanish government in ratifying it. The bounds it gave us were far too narrow to suit the more fiery Western spirits, and these cheered Benton to the echo when he attacked it in public with fierce vehemence. "The magnificent valley of the Mississippi is ours, with all its fountains, springs, and floods; and woe to the statesman who shall undertake to surrender one drop of its water, one inch of its soil to any foreign power." So he said, his words ringing with the boastful confidence so well liked by the masterful men of the West, strong in their youth, and proudly conscious of their strength. The treaty was ratified in the Senate, nevertheless, all the old Southern States favoring it, and the only votes at any stage recorded against it being of four Western senators, coming respectively from Ohio, Kentucky, Tennessee, and Louisiana. So that in 1818, at any rate, the desire for territorial aggrandizement at the expense of Maine or Mexico was common to the West as a whole, both to the free and the slave states, and was not exclusively favored by the Southerners. The only effect of Benton's speech was to give rise to the idea that he was hostile to the Southern and Democratic administration at Washington, and against this feeling he had to contend in the course of his successful candidacy for the United States senatorship the following year, when Missouri was claiming admittance to the Union.
It was in reference to this matter of admitting Missouri that the slavery question for the first time made its appearance in national politics, where it threw everything into confusion and for the moment overshadowed all else; though it vanished almost as quickly as it had appeared, and did not again come to the front for several years. The Northerners, as a whole, desiring to "restrict" the growth of slavery and the slave-power, demanded that Missouri, before being admitted as a state, should abolish slavery within her boundaries. The South was equally determined that she should be admitted as a slave state; and for the first time the politicians of the country divided on geographical rather than on party lines, though the division proved but temporary, and was of but little interest except as foreshadowing what was to come a score of years later. Even within the territory itself the same contest was carried on with the violence bred by political conflicts in frontier states, there being a very respectable "restriction" party, which favored abolition. Benton was himself a slave-holder, and as the question was in no way one between the East and the West, or between the Union as a whole and any part of it, he naturally gave full swing to his Southern feelings, and entered with tremendous vigor into the contest on the anti-restriction side. So successful were his efforts, and so great was the majority of the Missourians who sympathized with him, that the restrictionists were completely routed and succeeded in electing but one delegate to the constitutional convention. In Congress the matter was finally settled by the passage of the famous Missouri Compromise bill, a measure Southern in its origin, but approved at the time by many if not most Northerners, and disapproved by not a few Southerners. Benton heartily believed in it, announcing somewhat vaguely that he was "equally opposed to slavery agitation and to slavery extension." By its terms Missouri was admitted as a slave state, while slavery was abolished in all the rest of the old province of Louisiana lying north and west of it and north of the parallel of 36° 30'. Owing to an objectionable clause in its Constitution, the admission was not fully completed until 1821, and then only through the instrumentality of Henry Clay. But Benton took his seat immediately, and entered on his thirty years' of service in the United States Senate. His appearance in national politics was thus coincident with the appearance of the question which, it is true, almost immediately sank out of sight for a period of fifteen years, but which then reappeared to stay for good and to become of progressively absorbing importance, until, combining itself with the still greater question of national unity, it dwarfed all other issues, cleft the West as well as the East asunder, and, as one of its minor results, brought about the political downfall of Benton himself and of his whole school in what were called the Border States.
Before entering the Senate, Benton did something which well illustrates his peculiar uprightness, and the care which he took to keep his public acts free from the least suspicion of improper influence. When he was at the bar in St. Louis, real estate litigation was much the most important branch of legal business. The condition of Missouri land-titles was very mixed, since many of them were based upon the thousands of "concessions" of land made by the old French and Spanish governments, which had been ratified by Congress, but subject to certain conditions which the Creole inhabitants, being ignorant and lawless, had generally failed