Clark biographer Landon Y. Jones notes: "For 30 years after the expedition, William Clark ranked as the leading federal official in the West, the point man for six Presidents, from Jefferson to Van Buren, who trusted him with protecting American interests on territory bitterly contested by both Britain and Spain." Clark embodied the contradictions of his time; while he urged the government to treat Indians fairly, the treaties he brokered forced the relocation of tens of thousands. Clark died at age 68, in 1838, in the St. Louis home of his firstborn son, Meriwether Lewis Clark.
Seven years after her reunion with the Shoshone, Sacagawea and her husband turned up at Fort Manuel, a trading post near present-day Bismark, North Dakota, where Toussaint had found work as an interpreter with the Missouri Fur Company. Journalist Henry Brackenridge wrote that Sacagawea was ill "and longed to revisit her native country." She never got the chance. On December 20, 1812, John Luttig, the fort's chief clerk, wrote in his logbook that Sacagawea "died of a putrid fever she was a good and the best Women in the fort." She would have been about 25. She left behind two biological children: 7-year-old Jean Baptiste and 4-month-old Lisette.
The following year Luttig, possibly representing William Clark (for whom he had worked), petitioned the Orphans' Court in St. Louis for guardianship of Jean Baptiste and Lisette. (By then, Toussaint was presumed dead, having not been seen for six months.) Luttig's name was eventually crossed out on the petition and replaced with that of Clark, who, at the very least, paid for Baptiste's education. (Baptiste later traveled to Europe, where he remained for six years. Upon returning to the United States, he worked as a trapper with Jim Bridger and Kit Carson.) Lisette's fate, and that of Sacagawea's nephew, is unknown.
Over the course of the expedition, William Clark grew very fond of Sacagawea's baby, became his guardian and later financed his education at a St. Louis boarding school.
The known facts of Baptiste's life are few. In 1823, Duke Paul Wilhelm Friedrich Herzog of Wurttemberg, Germany, visited a trading post in present-day Kansas City, where he met the then 18-year-old man, who was working as a guide and interpreter. The two traveled to Europe, where Baptiste remained for six years. He fathered a child with a German woman, but the baby, a boy, died after three months, and Baptiste returned to the United States. He headed West, eventually working as a trapper with Jim Bridger and Kit Carson.
Baptiste settled in California, serving as alcalde, or magistrate, at the San Luis Rey Mission. In 1866, he joined gold prospectors headed for the Montana Territory. On the way, he developed pneumonia and died shortly thereafter, at age 61, in Oregon near the Idaho border, having outlived all of the members of the expedition except Sgt. Patrick Gass.
After the expedition ended, Clark traveled in 1807 to St. Louis to take up duties as chief Indian agent for the Territory of Upper Louisiana, bringing York with him. A rift developed between the two men: York had wanted to remain in Kentucky, near his wife, whom he hadn't seen in almost five years. He also petitioned Clark for his freedom—perhaps thinking of the double pay and 320 acres the other men received for their services on the expedition. These requests struck Clark as presumptuous coming from a slave. Clark eventually allowed York to return to Kentucky in 1808 for a short visit. But Clark wrote to his brother Jonathan: "If any attempt is made by york to run off, or refuse to provorm his duty as a Slave, I wish him Sent to New Orleans and Sold, or hired out to Some Severe master untill he thinks better of Such Conduct."
In a letter (now in the Jonathan Clark Papers—Temple Bodley Collection at the Filson Historical Society in Louisville) to his brother dated a few months later, Clark wrote: "I did wish to do well by him—but as he has got Such a notion about freedom and his emence Services, that I do not expect he will be of much Service to me again; I do not think with him, that his Services has been So great (or my Situation would promit me to liberate him)."