The Lewis and Clark expedition was the first official US-sponsored land survey to reach the Pacific overland, commissioned by President Thomas Jefferson after the Louisiana Purchase expanded US land to include the region from the Mississippi to the Rockies. The journey aimed to map the new territory, discover a navigable water route (with portages) from the Mississippi River to the Pacific Ocean, and establish diplomatic and trade ties with Native tribes.
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Follow the Corps of Discovery’s full route from St. Louis to the Pacific and back on Google Earth. Explore key camps, Native encounters, and natural landmarks through satellite imagery and on-the-ground photos.
Beyond seeking a water route to the Pacific, Jefferson tasked the Corps of Discovery with mapping the new Louisiana Territory, cataloging its resources, and establishing trade with Native nations.
Covering over 8,000 miles, William Clark’s maps charted rivers, mountains, and tribal territories with remarkable accuracy. Equipped with sextants, compasses, telescopes, and more, Clark became an expert at surveying—requiring extensive celestial and topographical observations each day.
Acquired from France for $15M, the Louisiana Purchase added 828,000 square miles to the United States—stretching from the Mississippi River to the Rockies. US ambassadors in France signed the papers to buy the tract from the embattled Napoleon Bonaparte for a mere $15M before Jefferson learned the terms, due to the advantageous nature of the deal.
Jefferson pushed for the Louisiana Purchase to prevent France or Spain from dominating the western frontier, securing control of the Mississippi River and vast lands that he felt were essential to America’s strategic and economic future.
For centuries, leaders pursued a direct seafaring trade route from Europe to Asia. Jefferson joined this quest by sending Lewis and Clark west, though they confirmed no such practical interior route existed across the continent.
Hailing from Jefferson’s Albemarle County neighborhood in Virginia, Lewis was a trusted aide and former Army officer. After leading the Corps of Discovery, he became Louisiana Territory governor in 1806, dying three years later under mysterious circumstances.
After the expedition, Clark held key territorial and federal roles, overseeing western expansion and Native relations. While he expressed sympathy for displaced natives, he oversaw the transfer of millions of acres from Native nations to US control through various treaties.
York, Clark’s enslaved servant, played a full role in the expedition—hunting, scouting, and aiding diplomacy with Native nations who were fascinated by his appearance. Despite his contributions, York remained enslaved for some time after the journey, though its uncertain if he remained so for the rest of his life. Explore every member of the Corps of Discovery here.
Preparing for two years in the wilderness, Lewis acquired hundreds of supplies, including medicine, food, weapons, and 63 lbs of pigtail tobacco. The total bill was estimated to be around $2,324 (around $60,000 today).
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