When Jefferson took office in 1801, most of the United States population lived within 50 miles of the Atlantic Ocean. Knowledge of the western part of the continent was limited to what had been learned from French traders and fur trappers and Spanish and British explorers. On January 18, 1803, President Jefferson sent a secret letter to Congress asking for $2,500 to fund an expedition to the Pacific Ocean. He hoped to establish trade with the Native American people of the West and find a water route to the Pacific. Jefferson also was fascinated by the prospect of what could be learned about the geography of the West, the lives and languages of the Native Americans, the plants and animals, the soil, the rocks, the weather, & how they differed from those in the East.
President Jefferson's choice to lead an expedition was Meriwether Lewis, his former secretary & a fellow native of Albemarle County, Virginia.
While Lewis was in Washington in July 1803, the United States's purchase of the Louisiana territory from France was announced. Now the journey was even more important. Lewis and his party would be exploring land that belonged to the United States. Armed with Jefferson's letter of instructions, Lewis traveled to Pittsburgh and then set out on the Ohio River. At Clarksville, in present-day Indiana, he met up with William Clark. They packed the keelboat, which Lewis had designed, and two pirogues (canoe-like boats) with supplies and headed downriver. They were accompanied by some recruited soldiers, Clark's African-American slave York, and Lewis's Newfoundland dog Seaman.
President Jefferson's instructions to Lewis were so extensive as to be almost impossible to fulfill, yet he viewed the Expedition as a tremendous success. The discoveries made by the explorers changed the vision of this young country. No water route to the Pacific was found, but accurate and detailed maps were drawn. Peaceful contact was made with Native American tribes and trade was discussed. The body of knowledge added to the scientific community proved to be truly invaluable and vast reaches of North America had been explored. Lewis and Clark's "voyage of discovery" turned out to be one of Thomas Jefferson's most enduring legacies.