Once across the divide, the early stream of immigration took its way down the Ohio River to the Mississippi.  There it met the outposts of French power, for the French burst open that great river, following their missionaries, Marquette and Joliet, down from its headwaters in Wisconsin, or pressing up from their early settlements at New Orleans.  Doubtless, if it had not been that the Mississippi afforded the most practicable, and the most useful highway from north to south, the young American people would have had a French State to the westward of them until they had gone much further on the path toward national manhood.  But the navigation of the Mississippi and its tributaries was so rich a prize, that it stimulated alike considerations of individual self-interest and national ambition.  From the day when the first flatboat made its way from the falls of the Ohio to New Orleans, it was the fixed determination of all people living by the great river, or using it as a highway for commerce, that from its headwaters to its mouth it should be a purely American stream.  It was in this way that the Mississippi and its tributaries proved to be, as I have said, a great influence in developing the spirit of coherent nationality among the people of the young nation.

Indeed, no national Government could be of much value to the farmers and trappers of Kentucky and Tennessee that did not assure them the right to navigate the Mississippi to its mouth, and find there a place to trans-ship their goods into ocean-going vessels.  From the Atlantic seaboard they were shut off by a wall, that for all purpose of export trade was impenetrable.  The swift current of the rivers beat back their vessels, the towering ranges of the Alleghanies mocked at their efforts at road building.  From their hills flowed the water that filled the Father of Waters and his tributaries.  Nature had clearly designed this for their outlet.  As James Madison wrote:  “The Mississippi is to them everything.  It is the Hudson, the Delaware, the Potomac, and all the navigable waters of the Atlantic coast formed into one stream.”  Yet, when the first trader, in 1786, drifted with his flatboat from Ohio down to New Orleans, thus entering the confines of Spanish territory, he was seized and imprisoned, his goods were taken from him, and at last he was turned loose, penniless, to plod on foot the long way back to his home, telling the story of his hardships as he went along.  The name of that man was Thomas Amis, and after his case became known in the great valley, it ceased to be a matter of doubt that the Americans would control the Mississippi.  He was in a sense the forerunner of Jefferson and Jackson, for after his time no intelligent statesman could doubt that New Orleans must be ours, nor any soldier question the need for defending it desperately against any foreign power.  The story of the way in which Gen. James Wilkinson, by intrigue and trickery, some years later secured a partial relaxation of Spanish vigilance, can not be told here, though his plot had much to do with opening the great river.