William Clark, a soldier and explorer from Caroline County, Virginia, was asked in 1803 by Meriwether Lewis to join in leadership of an expedition to the Pacific Ocean across the newly acquired Louisiana Purchase and Rocky Mountains. He became the primary mapmaker and artist of the endeavor, as well as a gifted diarist. The following are excerpts from his journals:

Sunday May 13, 1804.

River Dubois opposet [sic] the Mouth of the Missourie River I dispatched an express this morning to Capt Lewis at St Louis, all our provisions goods and equipage on Board of a boat of 22 oars, a large Perogue of 71 oars, a second Perogue of 67 oars, Complete with sails &c Men compd With Powder Cartridges and 100 balls each, all in health and readiness to set out. Boats and everything Complete, with the necessary, stores of provisions 6c such articles...