Rendezvous were used as places appointed for assembling or meeting other traders before most forts were constructed. Most of the year the Mountain Men worked alone or in small groups. But once a year they trickled out of several million empty square miles and came together for the purposes that were at once commercial, practical, fraternal, and infernal.

This was the annual rendezvous - the highlight of the mountain man's year. For several weeks each summer, the mountain men met, drank, fought and lied to each other prodigiously. Wagon trains sent by the companies who supported their enterprise arrived bearing supplies and whiskey, and departed filled with tons of beaver hides. Groups of Indians also showed up to trade and watch the proceedings.

In 1813 John Reid started a fur trading post on the lower Boise River, but Bannock Indians wiped it out in 1814.

The Grand Tetons both on the Idaho and Wyoming side were among the first rendezvous sites. In 1829 a rendezvous was held at Pierre's Hole, now known as the Teton basin, where hundreds of mountain men and fur trappers congregated.