Final answer:
The Zebulon Pike expedition explored Colorado and attempted to find the starting point of the Red River in 1806, separate from the Lewis and Clark expedition.
Step-by-step explanation:
The expedition that explored Colorado and sought to find the starting point of the Red River in 1806 was known as the Zebulon Pike expedition. This is not to be confused with the more well-known Lewis and Clark expedition, which travelled from the Mississippi River across the Northwest to the Pacific Ocean from 1804 to 1806.
While Lewis and Clark were tasked with exploring the newly acquired western lands of the United States, mapping the territory, and assessing commercial possibilities and potential trade routes, Zebulon Pike's expedition focused on the southwestern part of the Louisiana Purchase, including Colorado, and was separate from the mission of Lewis and Clark.