As of the census of 2000, there were 122 people, 57 households, and 33 families residing in the CDP. The population density was 71.7 people per square mile (27.7/km²). There were 61 housing units at an average density of 35.9/sq mi (13.9/km²). The racial makeup of the CDP was 85.25% White, 10.66% Native American, and 4.10% from two or more races. Hispanic or Latino of any race were 0.82% of the population.
There were 57 households out of which 22.8% had children under the age of 18 living with them, 43.9% were married couples living together, 7.0% had a female householder with no husband present, and 42.1% were non-families. 36.8% of all households were made up of individuals and 12.3% had someone living alone who was 65 years of age or older. The average household size was 2.14 and the average family size was 2.82.
In the CDP the population was spread out with 23.8% under the age of 18, 4.1% from 18 to 24, 23.8% from 25 to 44, 31.1% from 45 to 64, and 17.2% who were 65 years of age or older. The median age was 43 years. For every 100 females there were 103.3 males. For every 100 females age 18 and over, there were 93.8 males.
The median income for a household in the CDP was $18,250, and the median income for a family was $28,125. Males had a median income of $36,250 versus $28,750 for females. The per capita income for the CDP was $9,598. There were 25.9% of families and 28.0% of the population living below the poverty line, including no under eighteens and 13.3% of those over 64.
In the state legislature Round Mountain is located in the 4th Senate District, represented by Republican Sam Aanestad, and in the 2nd Assembly District, represented by Republican Doug LaMalfa. Federally, Round Mountain is located in California's 2nd congressional district, which has a Cook PVI of R +13 and is represented by Republican Wally Herger.
On August 191992, a fire called the Fountain Fire started off Buzzard Roost Road. It destroyed approximately 600 structures in Round Mountain and the surrounding towns. The fire burned 64,000 acres, and also burned most of Round Mountain's neighbor, Montgomery Creek. Enough lumber to build 52,000 homes was also destroyed, and the towns were declared a disaster area. The town of Burney was threatened as well.