[1] 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.

Pike's company made several errors and ended up in Spanish territory in present-day Southern Colorado, where the Americans built a fort to survive the winter.

[2] Pike left Fort Bellefontaine near St. Louis, Missouri on July 15 with a detachment of 20 soldiers and 50 Osage hostages, freed for return to their people.

Upon traversing the Great Plains, Pike wrote, "This vast plains of the western hemisphere may become in time as celebrated as the sandy deserts of Africa; for I saw in my route, in various places, tracts of many leagues where the wind had thrown up the sand in all the fanciful form of the ocean's rolling wave, and on which not a speck of vegetable matter existed.

Pike next intended to travel to the headwaters of the Red River and head downstream to the Mississippi and relative safety in the lowlands.

Heading north, the party found the South Fork of the Platte River and, following it upstream, came to what they thought were the headwaters of the Red.

By January 30, he and the ten men still with him came to the Rio Grande at a point near Alamosa in present-day southern Colorado and then part of the Spanish empire.

On February 26, in the night Pike and his remaining men were captured at their fort by Spanish soldiers from nearby Santa Fe.

Chihuahua's Governor Salcedo released Pike and most of his men, as they were military officers of a neighboring country, with whom Spain was not at war.

The Spanish military escorted Pike and some of his party back north, through San Antonio, Texas, arriving at the border with Louisiana at Natchitoches on July 1, 1807.