In 1803 President Thomas Jefferson negotiated the Louisiana Purchase, nearly doubling the size of the country. One of the first official expeditions into the area was Merriwether Lewis and William Clark's journey into the Northwestern part of the territory, where they recorded detailed observations of the topography and collected wildlife specimens.

William Clark carried this compass during the expedition. The paper dial is marked "T.Whitney Philada.," identifying the maker, and set in a brass - bound mahogany box.