Lewis and Clark Timelines

The following timelines provide a chronological overview of the Lewis and Clark Expedition. They chronicle the major events of the expedition from April 20, 1803 to September 23, 1806.

Thomas Jefferson's Estate at Monticello.

Jefferson's Dream

Thomas Jefferson had a dream - one might almost say an obsession. It began in his youth, when his father, Peter Jefferson, was involved in a company promoting westward settlement to Kentucky and Tennessee. Peter was one of the first of the tidewater planters to move out to the Piedmont area of Virginia. He helped survey the state and create the Jefferson-Fry map of Virginia, published in London in 1751 under the Royal Geographer, Jeffreys. In 1749, Peter Jefferson, Joshua Fry, Dr. Thomas Walker, and James Maury formed the "Loyal Land Company" to buy and promote land purchases west of the Blue Ridge Mountains. Walker was the first non-Indian to cross the Blue Ridge into Kentucky, and charted the Cumberland Gap.


Peter Jefferson and his associates believed in a concept called symmetrical geography. This concept theorized that all North American rivers sprang from a single source, a great lake centered on the continent, called Thoyaga. Flowing from Thoyaga was a navigable river which flowed to the Pacific. They also believed that since river tributaries which flowed to the Atlantic passed so close to tributaries which led to the Mississippi, the same situation would probably hold true of Missouri River tributaries and Western rivers which flowed to the Pacific.

The Loyal Land Company dedicated their efforts to finding a passage through the mountains to the Pacific. This passage could make them very rich men - an easy way to the spices and minerals of the east, particularly China - a dream of explorers since the time of Columbus. The French and Indian War put an end to the land company's plan, of which ten-year-old Thomas Jefferson was surely aware. In fact, even after Peter Jefferson's death when his son was 14, one of the partners of the land company, James Maury, served as young Thomas' tutor. Maury described the Loyal Land Company plan:

Missouri River
This view of the Missouri River was taken from a bluff at Weston Bend State Park, north of Kansas City.
Some persons were to be sent in search of that river Missouri, if that be the right name of it, in order to discover whether it had any communication with the Pacific Ocean; they were to follow the river if they found it, and make exact reports of the country they passed through, the distances they traveled, what worth of navigation those rivers and lakes afforded, &c.

As Thomas Jefferson matured and achieved success in several fields, he never lost sight of his father's plan. He tried several times to encourage or promote the exploration of the American continent. Jefferson's interest in the West stemmed from his lifelong scientific curiosity, and was sustained by his hopes for the future of the United States. In 1783, at the end of the American Revolution, Jefferson was concerned that the British might secure a foothold west of the Mississippi. He asked the war hero George Rogers Clark to consider leading a privately sponsored expedition to explore the area, but Clark declined. In 1786, while serving as U.S. minister to France, Jefferson met John Ledyard. An American veteran of Captain James Cook's third voyage to the Pacific, Ledyard planned to cross Siberia, sail across the Pacific to the Northwest coast of America, and walk from west to east across the continent. Jefferson encouraged Ledyard, whose plans failed when the Russian government arrested and deported him before he left Asia. While serving as Secretary of State, Jefferson and the American Philosophical Society encouraged expeditions to be led by Dr. Moses Marshall in 1792 and the French botanist Andre Michaux in 1793, but these never got beyond the planning stages.

These last expeditions were spurred by momentous news from the West. In 1792 the American sailor Robert Gray discovered and mapped the mouth of the Columbia River, which provided evidence that there was indeed a major river which flowed out of the Rocky Mountains to the Pacific. If the headwaters of the Missouri River were located near the headwaters of the Columbia, an easy route across the continent might be located and mapped.

Portrait of Thomas Jefferson
In 1800 Thomas Jefferson was elected President of the United States, and upon taking office decided to act upon his old dream of a trans-continental expedition. By 1800 Spanish, French, English and American traders and explorers had gained a reasonably good knowledge of the Missouri River as far the Platte, and a lesser acquaintance for the 1,000 miles beyond to the Mandan Indian villages in what is today North Dakota. British explorer Alexander MacKenzie had traveled over the Canadian Rockies to the Pacific in 1793, and this caused Jefferson great anxiety, for he feared that the British claim to the Pacific northwest would prevent American commerce in that region. Virtually nothing was known of the continent between the upper Missouri River and the Pacific coastal region, but the belief that the Missouri and Columbia rivers were interlocked and formed a "northwest passage" across the continent was popular.

For these reasons, in 1802 President Jefferson began to organize an official, government-sponsored expedition which would travel up the Missouri River and overland to the Pacific Ocean. He chose Meriwether Lewis, his personal secretary, to lead it.

Last updated: April 10, 2015

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