History: American Old West, United States

The new nation began to exercise some power in domestic and foreign affairs. The British had been driven out of the East after the American Revolutionary War but remained in Canada and threatened to expand into the Northwest. The French had left the Ohio Valley but still owned the Louisiana Territory from the Mississippi River west to the Rockies, including the strategic port of New Orleans. Spain's dominion (New Spain) included Florida and the territories from present-day Texas to California along the southern tier and up to what later would be Utah and Colorado.
With a stroke of the pen, Thomas Jefferson, the third president of the United States (elected in 1800), more than doubled the size of the United States with the Louisiana Purchase of 1803 which acquired land France had acquired from Spain just three years earlier. Napoleon Bonaparte had begun to consider it a liability, since the slave rebellion in Haiti and tropical disease undermined his Caribbean adventures. Robert R. Livingston, American ambassador to France, negotiated the sale with French foreign minister Talleyrand, who stated, "You have made a noble bargain for yourselves, and I suppose you will make the most of it".
The price was $15 million (about $0.04 per acre), including the cost of settling all claims against France by American citizens. The purchase was controversial. Many of the Federalist Party, the dominant political party in New England, thought that the territory was "a vast wilderness world which will... prove worse than useless to us" and spread the population across an ungovernable land, weakening federal power to the detriment of New England and the Northeast. But the Jeffersonians thought the territory would help maintain their vision of the ideal republican society, based on agricultural commerce, governed lightly and promoting self-reliance and virtue.
Jefferson quickly ordered exploration and documentation of the vast territory. He charged Lewis and Clark to lead an expedition, starting in 1804, to "explore the Missouri River, and such principal stream of it, as, by its course and communication with the waters of the Pacific Ocean; whether the Columbia, Oregon, Colorado or any other river may offer the most direct and practicable communication across the continent for the purposes of commerce". Jefferson also instructed the expedition to study the region's native tribes (including their morals, language, and culture), weather, soil, rivers, commercial trading, animal and plant life.