San Ardo (formerly, San Bernardo) is a census-designated place (CDP) in Monterey County, California, United States. San Ardo is located 18 miles (29 km) southeast of King City, at an elevation of 449 feet (137 m). The population was 501 at the 2000 census.
San Ardo is near the point where the broad Salinas Valley ends at its southern terminus and pinches out between the California Coast Ranges including the Santa Lucia Mountains on the west and the inland hills of the Cholame Hills and the Diablo Range on the east.
According to the United States Census Bureau, the CDP has a total area of 0.4 square miles (1.2 km²), all of it land.
The owner of the San Bernardo land grant, M.J. Brandenstein, laid out the town when the railroad reached his land in 1887. The San Bernardo post office opened in 1886, and changed its name to San Ardo in 1887.
As of the census of 2000, there were 501 people, 157 households, and 110 families residing in the CDP. The population density was 1,114.6 people per square mile (429.9/km²). There were 167 housing units at an average density of 371.5/sq mi (143.3/km²). The racial makeup of the CDP was 47.90% White, 0.40% African American, 2.40% Native American, 0.40% Asian, 46.91% from other races, and 2.00% from two or more races. Hispanic or Latino of any race were 65.67% of the population.
There were 157 households out of which 41.4% had children under the age of 18 living with them, 47.1% were married couples living together, 10.2% had a female householder with no husband present, and 29.3% were non-families. 24.2% of all households were made up of individuals and 7.6% had someone living alone who was 65 years of age or older. The average household size was 3.19 and the average family size was 3.82.
In the CDP the population was spread out with 35.3% under the age of 18, 11.8% from 18 to 24, 27.7% from 25 to 44, 15.8% from 45 to 64, and 9.4% who were 65 years of age or older. The median age was 27 years. For every 100 females there were 106.2 males. For every 100 females age 18 and over, there were 114.6 males.
The median income for a household in the CDP was $25,208, and the median income for a family was $31,500. Males had a median income of $30,417 versus $14,375 for females. The per capita income for the CDP was $11,379. About 15.4% of families and 24.0% of the population were below the poverty line, including 32.5% of those under age 18 and 13.5% of those age 65 or over.