Born in Virginia, Ashley moved to Missouri, and entered into a venture which eventually became one of the most significant fur trade companies in the West.  In 1825, he led a group of fur trappers to the upper Green where Ashley decided to combine trapping with exploring.  After building bullboats by stretching buffalo hides over willow frames, he embarked on the first known attempt by whites to navigate the Green.

In Red Canyon, where the group stopped to carry their boats and gear past a rapid, Ashley inscribed ASHLEY 1825 on a rock in large black letters.  This inscription was noted by Powell’s men 44 years later.  In Split Mountain Canyon, Ashley nearly drowned when his boat swamped, with only quick action by his men saving his life.

In the Uinta Basin, Ashley and his men encountered a party of Taos trappers from New Mexico, who advised him not to continue down the river.  Instead, he joined them in traveling back to the north and to the first mountain man rendezvous, held near the Henry’s Fork River, north of the Uinta Mountains.  Ashley made his fortune and left the fur trade, while several of his companions on the river, such as Thomas Fitzpatrick and William Sublette, became some of the most famous names in the Rocky Mountain fur trade.