Thomas Jefferson (1743-1826) is considered one of the Founding Fathers of the United States of America for the central role he played in drafting the Declaration of Independence. During the American Revolution, Jefferson was elected governor of Virginia and, after the war, he was appointed minister to France. He also served as the nation's first secretary of state, its second vice president, and its third president.
In 1803, Jefferson approved the Louisiana Purchase, in which the U.S. bought a vast expanse of territory between the Mississippi River and the Rocky Mountains from France. Though the purchase violated Jefferson's own constitutional principles, he felt it was an opportunity too significant to pass up. The next year, Jefferson dispatched the Lewis & Clark expedition to explore the new lands en route to the Pacific.