Sierra County is located in the Sierra Nevada mountain range of California, northeast of Sacramento on the border with Nevada. As of 2000 the population was 3,555. The county seat is the town of Downieville. The only incorporated city in the county is Loyalton.

Sierra County was formed from parts of Yuba County in 1852. The county derives its name from the Sierra Nevada.

As of the census of 2000, there were 3,555 people, 1,520 households, and 986 families residing in the county. The population density was 4 people per square mile (1/km²). There were 2,202 housing units at an average density of 2 per square mile (1/km²).

County Website: www.sierracounty.ws/

School District: http://www.sierra-coe.k12.ca.us/