After the completion of the Lewis and Clark expedition, William Clark conducted a diplomatic expedition into the Missouri Territory where he would later serve as governor and superintendent of Indian affairs at St. Louis. His 1808 diary (8/25-9/22) recounts his journey to form a treaty with the territory's Osage Indians. In addition to detailed accounts of daily events, including interactions with indigenous peoples, this volume features a sketch that may have served as the basis of Clark's Fort Osage map (9/16/1808). Researchers interested in the early national period, U.S. midwestern exploration, and native diplomacy ought to find the journal particularly compelling.
 

The Lewis and Clark Journals are among the most treasured and well-known collections at the American Philosophical Society. These 30 manuscript journals provide a detail record of the travels of Lewis and Clark to the source of the Missouri River and across the continent to the Pacific Ocean, including interlineations by Nicholas Biddle, who later published the narrative "History of the Expedition of Captains Lewis and Clark" (1814). Interested researchers may refer to the Finding Aid for a detailed account of the collection. Scholars researching the Lewis and Clark Expedition and western exploration in the early national period may choose to complement these volumes by paging the Meriwether Lewis Journal (Mss.917.3.L58), which provides an early account of the river trip from Pittsburgh to the winter camp of the expedition (1803), and the William Clark Diary (Mss.917.3.L58c), which details Clark's diplomatic expedition into the Missouri Territory after the expedition (1808).