Interested in scientific knowledge and exploration, and desirous of keeping American ships off the seas by developing internal trade, Jefferson had anticipated the purchase of Louisiana by proposing confidentially to Congress the despatch of a few men on an investigating trip up the Missouri River. Trade with the Indians needed to be cultivated in this manner, but no State was sufficiently concerned to undertake it. Jefferson found an easy way to warrant national action. "The interests of commerce," said he, "place the principal object within the constitutional powers and care of Congress." Not even Randolph, who deplored every departure from old policies, could ever regret the expenditure of the $2500 which sent the Lewis and Clark expedition across the continent and laid the claims for national addition nearly a half-century later. After this precedent, it was easy to send Lieutenant Pike to ascertain the true source of the Mississippi and to explore the vast plains on the south-west toward the Spanish possessions. Many expeditions for scientific purposes and for exploration have been sent by the National Government since that day; but it must be remembered that the practice was inaugurated under the strict constructionists, with no other warrant than "to regulate commerce."
The Lewis and Clark expedition called fresh attention to the possibilities of the great West, and justified the urgent demand of the Western people for national aid. The danger of Western secession had long since disappeared; but many plotters had shown a tendency to use the frontiersmen as allies in the European wars. Genet, over ten years before the Lewis and Clark expedition, contemplated the use of an American force against British Canada. Miranda proposed to use the same recruiting-ground for his movements on Spanish South America, and even Hamilton consented to the scheme, if he could be commander of the expedition. Now came Burr, planning an expedition of these hardy trans-Alleghenians into New Orleans and thence into the disintegrating Spanish possessions of the South-west. Napoleon's success seemed to have turned the heads of all ambitious men of the day toward foreign conquest and they proposed to use the Mississippi valley as a rallying-ground. To invade the territory of a nation with whom the United States was at peace was contrary to Federal law. Jefferson turned his attention toward punishing Burr on even more serious grounds; but Gallatin was keen enough to discover the cause for selecting the Western people as tools. It was not a novel idea to suggest better means of communication between the East and the West; but it was novel to attribute Western disaffection to a lack of touch and sympathy between the people of the two sections. Trade and intrigue with foreign neighbours, so Gallatin thought, could be suppressed more easily by kindness than by punishment. It was true that the National Government had permanently opened the Mississippi River as an outlet for the West. But the journey down was long and tedious, delays might be encountered at New Orleans because of the limited number of ocean vessels on which produce could be transshipped, and only a limited cargo if any was possible on the return journey up-stream. The increase in population and the consequent increase in the size of crops to be transported to a market would speedily bring a demand for some means of taking the products directly to the Atlantic seaboard and of bringing manufactured goods in return.