Captain William Clark, the red-haired co-captain of the Corps of Discovery, was born on August 1, 1770. Originally from the same area of Virginia that was home to both Jefferson and Lewis, Clark’s parents relocated their family near the Rappahannock River, where William was born. Clark began his military career at age 19 when he joined the Kentucky Militia. He later joined the regular army and was promoted to lieutenant. By 1795, he had received successive promotions to leadership positions, eventually attaining the rank of Captain. Ensign Meriwether Lewis was among men assigned to Clark. The two struck up a lasting friendship that would lead to their co-commanding the Corps of Discovery.
The increased importance of the exploration warranted an additional commander to assist Lewis, President Jefferson’s first choice to lead the journey. Lewis wanted William Clark. In mid October, Clark joined Lewis at Clarksville, Indiana Territory, opposite Louisville. Proceeding on, the embryonic Corps of Discovery reached St. Louis in mid-December, 1803. As the Corps proceeded on to the Pacific, Clark continued to keep careful compass records, measure distances and produce detailed strip maps for areas between major landmarks. The maps included notes on native botanical and zoological specimens and on potential mineral deposits.
In late October 1806, after completing the expedition and returning to St. Louis, Lewis and Clark led a cavalcade eastward that included Mandan and Osage Indian representatives. The pack train was loaded with whatever “plants, seeds, bird skins, animal skeletons, and furs [that] had not been ruined in water-soaked caches,” in addition to their journals and Clark’s large map of the American West. On January 5, 1808, Clark married Julia Hancock in Fincastle, Virginia. Julia would later bear Clark a son, whom they would name Meriwether Lewis Clark in honor of his father's closest partner. That summer, Clark became a business partner in the newly formed Missouri Fur Company, which planned to send militia units, hunters, and boatsmen up the Missouri to develop the American fur trading industry.
In Louisville, on October 11, 1809, the Clark family was told of Lewis’ death. Upon hearing the news, Clark traveled to Washington to visit the grieving Jefferson and Lewis family members. He would later go to Philadelphia to arrange for the rewriting of their journals, which were finally published in 1814 with Clark’s map as a supplement. In 1813, Clark was named Governor of the Missouri Territory until the state of Missouri was created in 1820. Although he was defeated in the first election for state governor, Clark continued enjoy his Brigadier General rank, and to serve as the Superintendent of Indian Affairs. Throughout the remainder of his life, he garnered the respect of Native Americans, traders and trappers alike. They brought new information to him regularly, which he was able to use to update his master map of the American West, a map that reflected the fast-changing face of a nation that now stretched from coast to coast. Clark died of natural causes in St. Louis, September l, 1838.