This stream rises near the boundary between Montana and the British possessions, and flows into the Missouri, where the modern town of Ophir is built.

The men left at the great falls were to dig up the canoes and baggage that had been cached there the previous year, and be ready to carry around the portage of the falls the stuff that would be brought from the two forks of the Jefferson, later on, by Sergeant Ordway and his party.

It will be recollected that this stuff had also been cached at the forks of the Jefferson, the year before.

The two parties, thus united, were to go down to the entrance of Maria's River into the Missouri, and Captain Lewis expected to join them there by the fifth of August; if he failed to meet them by that time, they were to go on down the river and meet Captain Clark at the mouth of the Yellowstone.

This explanation is needed to the proper understanding of the narrative that follows; for we now have to keep track of three parties of the explorers.
Captain Lewis and his men, having travelled northwest about twenty miles from the great falls of the Missouri, struck the trail of a wounded buffalo.