As of the census of 2000, there were 1,427 people, 468 households, and 335 families residing in the CDP. The population density was 852.3 people per square mile (329.9/km²). There were 503 housing units at an average density of 300.4/sq mi (116.3/km²). The racial makeup of the CDP was 63.28% White, 1.47% African American, 2.73% Native American, 0.42% Asian, 23.83% from other races, and 8.27% from two or more races. Hispanic or Latino of any race were 32.66% of the population.
There were 468 households out of which 46.6% had children under the age of 18 living with them, 52.4% were married couples living together, 12.2% had a female householder with no husband present, and 28.4% were non-families. 20.1% of all households were made up of individuals and 7.1% had someone living alone who was 65 years of age or older. The average household size was 3.03 and the average family size was 3.53.
In the CDP the population was spread out with 33.0% under the age of 18, 11.0% from 18 to 24, 32.1% from 25 to 44, 17.6% from 45 to 64, and 6.3% who were 65 years of age or older. The median age was 29 years. For every 100 females there were 104.7 males. For every 100 females age 18 and over, there were 108.3 males.
The median income for a household in the CDP was $33,264, and the median income for a family was $32,847. Males had a median income of $26,216 versus $20,134 for females. The per capita income for the CDP was $15,444. About 6.1% of families and 10.2% of the population were below the poverty line, including 14.5% of those under age 18 and 14.0% of those age 65 or over.
In the state legislature San Miguel is located in the 15th Senate District, represented by Republican Abel Maldonado, and in the 33rd Assembly District, represented by Republican Sam Blakeslee. Federally, San Miguel is located in California's 22nd congressional district, which has a Cook PVI of R +16 and is represented by Republican Kevin McCarthy.
The local government organization is the San Miguel Community Services District (CSD) which was started by Gregory G. Campbell a local resident. Mr Campbell created the CSD with the help of a petition that included signatures of over 80% of the local voters. The CSD is responsible for providing fresh water, sewer, fire protection and street lighting to the community of San Miguel.