Their mission was to explore the territory of the Louisiana Purchase, establish trade with, and sovereignty over the natives near the Missouri River, and claim the Pacific Northwest and Oregon Country for the United States before European nations. They also collected scientific data, and information on indigenous nations. President Thomas Jefferson appointed him Governor of Upper Louisiana in 1806. He died of gunshot wounds in what was either a murder or suicide, in 1809. The Louisiana Purchase was not made official until July 1803, Jefferson still requested Congress to fund the expedition in January of the same year.