At Soda Springs the company of emigrants split in two. The more cautious of them took the advice of their trail guide and remained on the Oregon Trail, but 32 men, plus Mrs. Kelsey and her baby, stuck to their original aim of heading for California.

One of the reasons that they felt confident in doing so, in spite of the warnings of Fitzpatrick and the unexplored nature of the Great Basin, was that they had a map. How were they to know that it was wrong? How should they know that the mapmaker had filled in the empty sections with hearsay and fabrications?

A misleading map of North America by Henry S. Tanner, 1822. The smaller of the two lakes is labeled Salt Lake, with the Buenaventura River flowing right to the Pacific..

According to Dawson:

We knew nothing positive about the route, except that it went west. True, we had some old maps picturing a river called Buenaventura, or St. Mary’s river, which, flowing out of Great Salt Lake and pursing a westerly course emptied into the Pacific; and from this map we thought all we should have to do was to find our river and follow it. However, we had been told by trappers that there was no river flowing from the lake, but that there was a river (which they called Ogden’s) that had its source west of the lake and flowed west, and that it might take us to California.

The trappers were right about Ogden’s river (also called Mary’s and later, Humboldt), but even they did not know about the Sierra Nevada. The company found the river, and faithfully followed it, expecting it to lead them to the shores of the Pacific. Alas—

The river seemed to be dwindling instead of receiving big tributaries to swell its flood and guide us into the plains of California and on to the Pacific, where our suffering and troubles would end, and where we could eat, eat, eat – and something that had some fat in it. But the route was getting more nearly impassable; and alas! What meant those big mountains ahead with no opening through them?