- One of the first Europeans to explore Colorado. He was a member of the Villasur expedition, which traveled from New Mexico to the Platte River in search of French traders.
Zebulon Pike (1806-1807)
- American explorer who led an expedition to explore the headwaters of the Arkansas River. He gave his name to Pikes Peak, which he named after himself.
Stephen Harriman Long (1820)
- American explorer who led an expedition to explore the Great Plains and Rocky Mountains. He gave his name to Longs Peak, which he named after himself.
John C. Fremont (1842-1843)
- American explorer who led several expeditions to the Rocky Mountains. He gave his name to Fremont Pass, which he named after himself.
Kit Carson (1842-1843)
- American frontiersman and explorer who accompanied John C. Fremont on his expeditions to the Rocky Mountains. He gave his name to Carson Peak, which he named after himself.