South Pass and William Henry Ashley

I'm reading a book about the early exploration of the American West, before and after the Louisiana purchase. One of the most significant finds by explorers was South Pass, a pass that allowed relatively easy passage over the Rocky Mountains and the Continental Divide. I don't live too far away from South Pass but was never aware of its existence or importance until reading about it.

In 1822 Ashley and business partner Andrew Henry -- a bullet maker whom he met through his gunpowder business -- posted famous advertisements in St. Louis newspapers seeking one hundred "enterprising young men . . . to ascend the river Missouri to its source, there to be employed for one, two, or three years." The men who responded to this call became known as "Ashley's Hundred." Between 1822 and 1825, Ashley and Henry's Rocky Mountain Fur Company, did several large scale fur trapping expeditions in the mountain west. Ashley's men are officially credited with the American discovery of South Pass in the winter of 1824. Ashley devised the rendezvous system in which trappers, Indians and traders would meet annually in a predetermined location to exchange furs, goods and money. His innovations in the fur trade earned Ashley a great deal of money and recognition, and helped open the western part of the continent to American expansion. In 1828 he explored present-day northern Colorado, ascending the South Platte River to the base of the Front Range, then ascending the Cache la Poudre River to the Laramie Plains and onward to the Green River.