Early America's Most Important Expeditions: The History of the Lewis and Clark Expedition and Zeb

Throughout his presidency at the beginning of the 19th century, Thomas Jefferson had worried about the future of the western U.S., seeing that settlements in the Ohio Valley and lower South relied upon the Mississippi River. France's controls over the region, in his estimation, put the U.S. at a severe disadvantage. His solution proved successful beyond his wildest imagination, for Napoleon did not only sell New Orleans to the U.S, the portion that Jefferson instructed his ministers to make an offer on, but all of "New France," the entire area of Louisiana. Jefferson might have said later that his purchase of the territory "strained" but did not "break" the Constitution, but also should have boasted that, with one stroke, he had removed one less obstacle to American expansionism. The Louisiana Purchase encompassed all or part of 15 current U.S. states and two Canadian provinces, and it allowed Jefferson to plan something he had talked about since taking office: an expedition deep into the unmapped and largely unknown continent with the final destination being the Pacific Ocean. This could prove the most significant of the goals that Jefferson - a person who thought of himself as a scientifically-minded thinker - wanted to accomplish as president.
In the aftermath of the Louisiana Purchase, the Lewis and Clark expedition was a much-heralded blow for American rights in the face of international competition, but that was only one of four expeditions authorized by Jefferson. Four years before Lewis and Clark set off, an army officer from New Jersey led two long-distance treks, one northward to the headwaters of the Mississippi River and the other to the Southwest. These were the only expeditions authorized by Jefferson while they were already en route, planned and launched by subordinates within the military. Indeed, the career of Zebulon Pike was "dominated by ambiguously motivated explorations of the American West."