<P> Third American President Thomas Jefferson ranked the Red River Expedition second in importance only to the Lewis and Clark Expedition to reach the Pacific Ocean through the Northwest . The Red River stretches west from its confluence with the Mississippi River across what is now the state of Louisiana and part of south - western Arkansas . Further west, the river forms the present - day southern border of Oklahoma where it meets Texas, and is now known to originate in the Texas Panhandle . </P> <P> After acquiring the lands of the Louisiana Purchase in 1804, Jefferson commissioned military groups to explore the unfamiliar territory and to collect scientific data about flora and fauna, topography, and ethnography of the many Native American peoples . By sending a group of explorers up the Red River, Jefferson wanted to verify reports that the river could provide a water route to Santa Fe in New Mexico (then part of New Spain). Other goals were to build trade and political relationships with the various tribes of American Indians, and to locate the Louisiana Purchase's southwestern and western borders with New Spain . </P> <P> In 1805 and early 1806, the President began to appoint leaders for the expedition . For the scientists, he chose the astronomer / surveyor Thomas Freeman, (who had recently been with Andrew Ellicott on his survey of the southern boundary of the United States) and Peter Custis (the first academically trained naturalist to accompany an expedition, he was still a medical student in Philadelphia . He served as the group's botanist and ethnographer). Captain Richard Sparks was chosen to lead the military troops . As the departure date of the expedition grew closer, more soldiers were recruited until the group numbered twenty - four in all . </P> <P> President Jefferson persuaded Congress to fund the effort . He worked with foreign diplomats in Washington to convince them that the exploration was for scientific purposes and would not threaten their interests . Both Britain and France accepted the proposal, but Spain objected, as it also still claimed the lands to be explored which it had just been forced to turn the Louisiana territories over briefly to the French Emperor Napoleon I who had suddenly unexpectedly turned and sold the vast interior continental lands to the Americans the year before . It did not want an armed military expedition within or near its remaining territory . </P>

Who led an expedition to the edge of oklahoma