William Clark
Along with Meriwether Lewis, Clark led the Lewis and Clark Expedition of 1803 to 1806 across the Louisiana Purchase to the Pacific Ocean, and claimed the Pacific Northwest for the United States. Before the expedition, he served in a militia and the United States Army. Afterward, he served in a militia and as governor of the Missouri Territory. From 1822 until his death in 1838 (aged 68) he served as Superintendent of Indian Affairs.