<P> The Pike Expedition ( July 15 , 1806 -- July 1 , 1807 ) was a military party sent out by President Thomas Jefferson and authorized by the United States government to explore the south and west of the recent Louisiana Purchase . Roughly contemporaneous with the Lewis and Clark Expedition , it was led by United States Army Lieutenant Zebulon Pike , Jr. who was promoted to captain during the trip . It was the first official American effort to explore the western Great Plains and the Rocky Mountains in present - day Colorado . Pike contacted several Native American tribes during his travels and informed them of the new US rule over the territory . The expedition documented the United States ' discovery of Pikes Peak . After splitting up his men , Pike led the larger contingent to find the headwaters of the Red River . A smaller group returned safely to the US Army fort in St. Louis , Missouri before winter set in . </P>
<P> The Pike Expedition ( July 15 , 1806 -- July 1 , 1807 ) was a military party sent out by President Thomas Jefferson and authorized by the United States government to explore the south and west of the recent Louisiana Purchase . Roughly contemporaneous with the Lewis and Clark Expedition , it was led by United States Army Lieutenant Zebulon Pike , Jr. who was promoted to captain during the trip . It was the first official American effort to explore the western Great Plains and the Rocky Mountains in present - day Colorado . Pike contacted several Native American tribes during his travels and informed them of the new US rule over the territory . The expedition documented the United States ' discovery of Pikes Peak . After splitting up his men , Pike led the larger contingent to find the headwaters of the Red River . A smaller group returned safely to the US Army fort in St. Louis , Missouri before winter set in . </P>
who explored the southwestern portion of the louisiana purchase
who explored the southwestern portion of the louisiana purchase
Lieutenant Zebulon Pike , Jr.
Lieutenant Zebulon Pike , Jr.