DescriptionNamed by Capt. Meriwether Lewis on July 28, 1805, for the third president of the United States, this river, one of the 3 forks of the Missouri, finds its source in what we now call the Beaverhead, Big Hole, and Ruby rivers. In 1810, Andrew Henry and Pierre Menard constructed a post for the St. Louis Missouri Fur Company on the east bank of the Jefferson River, near the headwaters of the Missouri River.Personal NamesLewis, MeriwetherMenard, Andrew HenryMenard PierreContributing InstitutionMontana Historical Society Library and ArchivesGeolocation[1]
