October 1st. The stream had already attained the size of which we supposed Mary’s river to be, and yet its course was due NW. Distance 20 miles.

Still headed northwest, still wondering if this is the right river.

How much knowledge did they have about this river? How much had it been explored previously?

Other than that erroneous fictionalized map, their only information came from fur trappers at Fort Hall. That’s where four of the men went to seek a pilot.

They were able to learn very little of the region lying west of Salt Lake. Their information was to the effect that there was a great and almost impassable desert which we were liable to become involved in if we went too far to the south. That there was a stream running west which had been visited by one of the trappers belonging to the Hudson Bay Company, among whom it was known by the name of Mary’s or Ogden’s River. That we must try to strike that stream, for to the south of it we would find no feed for animals. That we must be careful not to go too far to the north, for if we did, we would become involved in a maze of canyons and streams with precipitous cliffs which led off into the Columbia River and where we should be sure to wander and starve to death. The fact was no one knew but little about that country. No one had been through to California by that route so far as we could learn.

1877 Dictation, in The Bidwell-Bartleson Party, edited by Doyce C. Nunis

And with no more information than that, they went into the unknown.

The Great Basin and this river that formed the highway across it had been explored, or endured, by fur trappers looking for beaver twice before the Bidwell-Bartleson Party came along.

The first recorded sighting of the river (other than by the natives) was on November 9, 1828, by Peter Skene Ogden, a fur trapper for the Hudson Bay Company.  Ogden explored the river for several hundred miles. He initially named the river “Unknown River”, since he had no idea where it came from or where it went, but later he named it “Paul’s River”, after one of his trappers who died on the expedition and was buried on the river bank.

Ogden later changed it again to “Mary’s River,” after his Native American wife, and this is the name those fur trappers at Fort Hall used.  Ogden, who couldn’t seem to make up his mind, later suggested calling it “Swampy River,” because it ended in a marshy sink.

Joseph Walker and Benjamin Bonneville led a band of trappers along the river all the way to California via the Humboldt River, the Humboldt Sink, the Carson Sink, and then up into the Sierra Nevada in 1833. They called the river “Barren River” for its lack of trees.  Washington Irving, who made Bonneville famous in 1837 with his book about the expedition, called it “Ogden’s River.” I wonder if John Bidwell read the book?

Finally in 1845 the river was explored by the “Pathfinder”, John C. Fremont. By his day the explorations of the German naturalist Alexander von Humboldt were well-known to all.  Humboldt had never been anywhere near the Humboldt River, but his other explorations were famous, so Fremont thought it fitting to give his name to this river. It’s certainly better than “Swampy River” or “Barren River.” Although I must admit “Unknown River” has a certain appeal.