The United States, under President Thomas Jefferson, purchased the territory of Louisiana from France in 1803. The purchase doubled the size of the country. 

Since the vast majority of the new territory was unexplored, Thomas Jefferson asked Meriwether Lewis to lead an expedition to find a route that connected the Mississippi River to the Pacific Ocean.

Lewis was an experienced frontiersman, but he knew of someone who was even better. As he picked his crew, he asked William Clark to be a co-leader in the expedition. 

On the left is a real receipt for the materials Lewis and Clark purchased for the expedition. The government provided them with a total of $2,500 for the trip. 

Lewis and Clark launched from Camp Wood in St. Louis in the summer of 1804. They went up the Missouri River until reaching Fort Mandan, where they spent the winter. 

After winter, the crew, whose name became the Corps of Discovery, set off again and traveled by river through Missouri and Montana until encountering the Shoshone Tribe, who helped them get across the mountains. Lewis and Clark developed diplomatic relations with the natives. 

After crossing the Bitterroot Mountains, the Corps of Discovery carved canoe-like boats that took them to the Columbia River, where they wintered (1805-1806) at Fort Clatsop, close to Oregon.

In 1806, the explorers returned home to report their findings to Jefferson. On the way home, they encountered many other tribes with whom they traded and developed diplomatic relations. 

In their journals, they described or drew many creatures they had never seen before. They also recorded many landscapes and maps of their journey, fulfilling the purpose of their expedition.