Meriwether Lewis
Meriwether Lewis was an American explorer, soldier, and politician best known for leading the Lewis and Clark Expedition with William Clark to explore the Louisiana Purchase and claim the Pacific Northwest for the United States. He later served as Governor of Upper Louisiana Territory before dying at age 35 in Tennessee, likely by suicide. Though not primarily an author, his expedition studies and writings paved the way for American westward expansion.
The Journals of Lewis and Clark (Lewis & Clark Expedition)
The Lewis and Clark Journals (Abridged Edition): An American Epic of Discovery (Lewis & Clark Expedition)
Journals of Lewis and Clark
History of the Expedition Under the Command of Captains Lewis and Clark to the Sources of the Missouri, Across the Rocky Mountains, Down the Columbia River to the Pacific in 1804-6
Travels to the Source of the Missouri River: Volume 2: And Across the American Continent to the Pacific Ocean 1804, 1805, and 1806 (Cambridge Library Collection - Travel and Exploration)