In extreme circumstances, wagons entered a stream at one point, and then ascended or descended the course of the stream to a favorable exit point. Campsites of some of the more important early explorers and emigrant parties are plotted as accurately as possible. Many of these, such as the Cornelius Gilliam company of 1844, rely on descriptions by participants. In this respect, the recollections of E. E. Parrish and John Minto are invaluable. Also, the observations of Lt. J. Henry Carleton in 1844 and 1845 are of importance.
Several limitations apply.
Parrish and Minto traveled with different divisions of Gilliam's company, and these divisions sometimes camped several miles apart. Clyman's 1844 campsites are based on his descriptions and travel distances, which appear to be remarkably accurate. Fremont's 1842 campsites are based on his observations of latitude and longitude. Taking his known campsite just beyond the Red Vermillion crossing as a base point would indicate that his latitudes were quite accurate, but his longitudes, as Fremont himself was aware, were very much in error. New calculations were published in later editions of his works, but these do not agree with modern readings.