At the 2010 census South San Gabriel had a population of 8,070. The population density was 9,684.6 people per square mile. The racial makeup of South San Gabriel was 2,198 White, 83 African American, 56 Native American, 3,990 Asian, 4 Pacific Islander, 1,427 from other races, and 312 from two or more races. Hispanic or Latino of any race were 3,444 persons. The census reported that 7,834 people lived in households, 7 lived in non-institutionalized group quarters, and 229 were institutionalized. There were 2,249 households, 874 had children under the age of 18 living in them, 1,249 were opposite-sex married couples living together, 393 had a female householder with no husband present, 211 had a male householder with no wife present. There were 96 unmarried opposite-sex partnerships, and 15 same-sex married couples or partnerships. 308 households were one person and 150 had someone living alone who was 65 or older. The average household size was 3.48. There were 1,853 families ; the average family size was 3.76. The age distribution was 1,648 people under the age of 18, 737 people aged 18 to 24, 2,108 people aged 25 to 44, 2,225 people aged 45 to 64, and 1,352 people who were 65 or older. The median age was 40.5 years. For every 100 females, there were 92.9 males. For every 100 females age 18 and over, there were 90.0 males. There were 2,353 housing units at an average density of 2,823.8 per square mile, of the occupied units 1,597 were owner-occupied and 652 were rented. The homeowner vacancy rate was 1.1%; the rental vacancy rate was 4.8%. 5,545 people lived in owner-occupied housing units and 2,289 people lived in rental housing units.
2000
At the 2000 census there were 7,595 people, 2,091 households, and 1,727 families in the CDP. The population density was 9,106.3 inhabitants per square mile. There were 2,166 housing units at an average density of 2,597.0 per square mile. The racial makeup of the CDP was 0.39% African American, 1.17% Native American, 33.34% Asian, 0.20% Pacific Islander, 19.93% from other races, and 4.24% from two or more races. Hispanic or Latino 64.96% of the population, and 11.72% White. Of the 2,091 households 37.6% had children under the age of 18 living with them, 57.6% were married couples living together, 17.7% had a female householder with no husband present, and 17.4% were non-families. 13.7% of households were one person and 6.5% were one person aged 65 or older. The average household size was 3.52 and the average family size was 3.85. The age distribution was 25.0% under the age of 18, 9.0% from 18 to 24, 29.0% from 25 to 44, 22.9% from 45 to 64, and 14.1% 65 or older. The median age was 36 years. For every 100 females, there were 95.5 males. For every 100 females age 18 and over, there were 93.5 males. The median household income was $51,136 and the median family income was $50,451. Males had a median income of $35,598 versus $30,091 for females. The per capita income for the CDP was $16,345. About 8.2% of families and 11.0% of the population were below the poverty line, including 11.6% of those under age 18 and 14.4% of those age 65 or over.
