Pierre Dorion Sr. (1740-1810) was an aging French-Canadian fur trader who had lived among the Yankton Sioux for over 20 years. Lewis and Clark hired him as an interpreter for councils with the Sioux nations along the Missouri River.
Dorion accompanied the expedition from the Platte River to the Yankton Sioux villages, serving as interpreter during the council at Calumet Bluff in late August 1804. His long residency among the Yankton gave him credibility and linguistic skills that the captains lacked.
After serving the expedition, Dorion continued as a trader and interpreter on the upper Missouri. His son, Pierre Dorion Jr., later served as interpreter for the Astorian expedition (1811-1813), and the younger Dorion’s wife Marie became famous for her survival after the massacre of her husband and other expedition members in 1814.
