The Federalists—who had predicted terrible things for the country from the new president they thought they detested—were surprised. They had forgotten that Thomas Jefferson was a gracious country gentleman with fine taste and a belief in people's natural goodness . The nation didn't fall apart under a Democratic-Republican administration. But it did change. In 1803, Jefferson bought a huge piece of land; some people thought it extravagant or worthless. It was all the land that France had claimed in North America, and was called Louisiana after a French king—Louis . The Louisiana Purchase cost $15 million, or about four cents an acre, and it doubled the nation's size. Jefferson said it was a vast new "empire for liberty." He wrote, "In seizing [Louisiana I] ... have done an act beyond the Constitution." And in another letter he explained, "But it is incumbent on those ... who accept great charges, to risk themselves on great occasions."

The new land stretched from the Mississippi River to the Rocky Mountains and maybe beyond. No one was sure how far it went. So someone had to find out what had been bought. How big was the territory, what was it like, and where did it end? The West was as unknown to white men in 1803 as most of outer space is today. Jefferson sent an expedition to investigate. To head the expedition he commissioned his shy personal secretary Meriwether Lewis, a dreamer and lover of science, along with a good-natured, talkative soldier and mapmaker, William Clark. They were to explore the vast reaches of the American West. Jefferson wrote: "the object of your mission is to explore the Missouri River and the water offering the best communication with the Pacific Ocean.... Your observations are to be taken with great pains and accuracy ."