Zebulon Pike's 1806 Expedition: Not South to the Rockies—West to Colorado & New Mexico

The question contains a directional error. Zebulon Pike did not leave St. Louis traveling southwest to the Rocky Mountains. In 1806, he departed St. Louis heading west—up the Missouri River, then overland—into present-day Colorado and parts of New Mexico.

Pike's 1806–1807 Expedition (The "Pike Expedition")

• Mission: Explore the southwestern Louisiana Purchase; find the Red River's source; assess Spanish settlements; gather intelligence.
• Route: St. Louis → Missouri River → Osage River → overland to Arkansas River → followed it into Colorado.
• Pikes Peak: Attempted to summit (Nov 1806); turned back by waist-deep snow, starvation risk. Named for him later.
• Spanish Capture: In early 1807, his party wandered into Spanish territory (San Luis Valley, CO / northern NM). Detained by Spanish troops, taken to Santa Fe, then Chihuahua, Mexico. Released July 1807 via Texas/Louisiana.

Why Not "Southwest"?

From St. Louis, the Rockies lie due west. "Southwest" would point toward the Ozarks/Ouachitas (Interior Highlands), not the Rockies. Pike went west, then slightly south into Colorado's Front Range.

His maps and journals provided the first American descriptions of the Southern Rockies and Great Plains—fueling westward expansion.