John C. Frémont had broken camp in California and headed east across the Great Basin to the vicinity of the Great Salt Lake and finally east across the Colorado Rockies.

He returns in August 1844 to Saint Louis, having verified the existence of the Great Salt Lake and the enormous interior drainage field that is the Great Basin, proving the nonexistence of the San Buenaventura River that was thought to flow from the Rockies to California, and showing that the South Pass is the route of choice through the mountains.