San Isidro was first listed as a
census designated place in the
2000 U.S. census.
2020 census As of the
2020 United States census, there were 187 people, 40 households, and 28 families residing in the CDP.
2000 census At the
2000 census there were 270 people, 94 households, and 70 families in the CDP. The population density was . There were 113 housing units at an average density of . The
racial makeup of the CDP was 95.19% White, 3.33% from other races, and 1.48% from two or more races. 98.52% of the population were Hispanic or Latino of any race. Of the 94 households 39.4% had children under the age of 18 living with them, 61.7% were married couples living together, 10.6% had a female householder with no husband present, and 25.5% were non-families. 24.5% of households were one person and 14.9% were one person aged 65 or older. The average household size was 2.87 and the average family size was 3.49. The age distribution was 32.6% under the age of 18, 5.6% from 18 to 24, 24.8% from 25 to 44, 22.6% from 45 to 64, and 14.4% 65 or older. The median age was 36 years. For every 100 females, there were 110.9 males. For every 100 females age 18 and over, there were 95.7 males. The median household income was $18,750 and the median family income was $20,313. Males had a median income of $15,625 versus $33,333 for females. The per capita income for the CDP was $8,965. 42.3% of the population and 35.9% of families were below the
poverty line. Out of the total population, 57.6% of those under the age of 18 and 7.1% of those 65 and older were living below the poverty line. ==Education==