Fort Osage was the second U.S. outpost built following the Louisiana Purchase. The site, overlooking the bends and currents of the Missouri River, was first observed on June 23, 1804 by Clark during the Voyage of Discovery as a likely spot for a fort. Clark wrote in his 1808 journal, "Rose early examined the Situation and the points of a Small Is[lan]d. which is opposite, found the River could be completely defended and Situation elegant, this Situation I had examined in the year 1804 and was delighted with it and am equally so now, ordered the Boats to be unloaded and tools got ready to work, and fixed on the spot for the fort and other buildings..." During its nineteen years of existence, Fort Osage received explorers and dignitaries, trappers, traders and the great Native American leaders. Today's Fort is a reconstruction from original plans still in existence in Washington, D.C.

The Journal of William Clark, On His Expedition to Establish Fort Osage,
August 25 to September 22, 1808.