Lewis, Meriwether, 1774-1809, American explorer, one of the leaders of the Lewis and Clark expedition, b. near Charlottesville, Va. He was a captain in the army and served in a number of campaigns against Native Americans before becoming (1801) secretary to his friend President Jefferson. Selected to head the expedition for a land route to the Pacific Ocean, he chose William Clark as his associate. Upon that successful venture Lewis's fame rests. In 1807 he was made governor of Louisiana Territory, with headquarters at St. Louis. In 1809, while traveling to Washington to prepare the journals of the expedition for publication, he died suddenly—either by murder or suicide—in a lonely inn on the Natchez Trace. The cause of his death is still the subject of controversy.