Sierra County was formed from the then-much larger Yuba County. One such case involved a young lady named Juanita, who was hung from a bridge in Downieville on July 5, 1851. She was the only woman to ever be lynched in California. A good historical site Historic HWY49 has pictures and much more. Until 1860, all supplies were brought in by mule trains, which sometimes included 75 animals, as there were no roads wide enough for wagons.
Sierra County is comprised of two very different regions.
On the west side of the crest of the Sierra it is mountainous and heavily forested, therefore supporting miners and loggers. It is one of the largest alpine valleys in the Sierra Nevada mountains. Its population has been devloted to cattle-raising and farming since 1853. Today, Loyalton is the largest town in the county, and the only incorporated one. Other towns in the valley include Sierraville, Sattley and Calpine.