Sierra County is a county located in California's Sierra Nevada, northeast of Sacramento on the border with Nevada. As of 2000 the population is 3,555. The county seat is Downieville. According to the U.S. Census Bureau, the county has a total area of 2,491 km² (962 mi²). 2,469 km² (953 mi²) of it is land and 22 km² (9 mi²) of it is water. The total area is 0.89% water. As of the census2 of 2000, there were 3,555 people, 1,520 households, and 986 families residing in the county. The population density was 1/km² (4/mi²). There were 2,202 housing units at an average density of 1/km² (2/mi²). The racial makeup of the county was 94.18% White, 0.20% Black or African American, 1.88% Native American, 0.17% Asian, 0.08% Pacific Islander, 1.04% from other races, and 2.45% from two or more races. 5.99% of the population were Hispanic or Latino of any race.