A 19th-century colored lithograph print shows a green river valley with trees between steep brown cliffs. A man in a hat and a horse are carefully descending a cliff face in the foreground.
Created for the Pacific Railway Survey reports, this 1856 print by John Mix Stanley shows the Marias River of what would become central Montana. Fort Benton is visible on top of a bluff in the middle distance. The Pacific Railway Survey was one of the major exhibitions that mapped the American West following the Louisiana Purchase of 1803. (Getty Images)

After Lewis and Clark: 5 mapping expeditions that defined the landscape of the American West

Original story by Kieran Mulvaney

Following the 1803 Louisiana Purchase, which essentially doubled the size of the fledgling United States, then-President Thomas Jefferson commissioned a series of expeditions to map the new holdings.

The most famous was led by Meriwether Lewis and William Clark, but later explorations produced material that was just as important to the young nation’s sense of self. They also sparked mass European-American settlement of the new territories, extending the nation’s push to displace and, in many cases, destroy Indigenous communities.

These expeditions were “a mixture of public and private, and scientific and not; they were a grab bag of intentions and motivation,” says Wrigley Institute faculty affiliate William Deverell, a USC history professor and Dornsife College divisional dean who studies the environmental history of the American West.

Through the new maps and the reports and images that accompanied them, many individuals living in the eastern half of the country became aware for the first time of the monumental and awe-inspiring landscape out West. The ecosystems, landforms, and wildlife were completely unfamiliar to most easterners, and were unlike anything found almost anywhere else on Earth.

In a story on the History Channel website, Deverell outlines the major mapping expeditions of this period and explains the impact they had on people’s conceptions of the environment that became the American West.

Read the full story on the History Channel website >>