In 1826 Jedediah Smith and his intrepid mountain men were the first U.S. citizens to make it to California from the eastern U.S., crossing the Great Basin desert over the Colorado River through the Mojave and into Southern California. The Mexican authorities were alarmed by his presence and ordered him to go back the same way he came. Right. Jedediah was on a mission and that mission was beavers.
In Europe from 1600 to the mid-1850s beaver hats were all the rage. The underfur of the beaver was especially fine and could be fashioned into any shape and make a hat that could stand up to the rain. Duh! That fur works very well for those water-loving rats. These hats became so expensive that only the very wealthy could afford them and were made especially fashionable by a man named Beau Brummell.
The demand for beavers nearly resulted in their extinction in Europe and fueled a major economic expansion into the New World. John Jacob Astor and his Hudson Bay Company made a fortune hunting and trapping beavers in the New World. In fact, the national animal of Canada is the beaver.
Jedediah Smith and his fellow trappers were basically held hostage by the fur companies. They had periodic gatherings in large valleys of the American West called mountain men rendezvous, whereby the trappers would bring all of their pelts and sell them to the fur companies, which in turn would sell the trappers all the materials they needed to continue their trapping. It was a closed loop and Smith fought to get to California where they could possibly establish trade directly with China, which was another large fur market.
Ignoring the order to leave, Jedediah Smith continued north into the Great Central Valley trapping beavers along the way. They first tried to cross the Sierra by following the American River, which by the way Smith named for his party. But the snow was too deep so they went a little south and crossed at what we now call Ebetts Pass. These tough men were the first white people to cross the Sierra Nevada and all of this because of beavers.