Rancho Santa Margarita first appeared as a
census designated place in the
1990 U.S. census; The census reported that 99.9% of the population lived in households, 0.1% lived in non-institutionalized group quarters, and no one was institutionalized. 100.0% of residents lived in urban areas, while 0.0% lived in rural areas. There were 17,188 households, out of which 37.0% included children under the age of 18, 60.9% were married-couple households, 5.0% were
cohabiting couple households, 21.9% had a female householder with no spouse or partner present, and 12.3% had a male householder with no spouse or partner present. 18.5% of households were one-person households, and 6.7% were one-person households with someone aged 65 or older. The average household size was 2.79. There were 13,048
families (75.9% of all households). The age distribution was 22.8% under the age of 18, 8.8% aged 18 to 24, 25.2% aged 25 to 44, 31.8% aged 45 to 64, and 11.4% who were 65years of age or older.
2010 census The
2010 United States census reported that Rancho Santa Margarita had a population of 47,853. The population density was . The racial makeup of Rancho Santa Margarita was 37,421 (78.2%)
White (67.0% Non-Hispanic White), 887 (1.9%)
African American, 182 (0.4%)
Native American, 4,350 (9.1%)
Asian, 102 (0.2%)
Pacific Islander, 2,674 (5.6%) from
other races, and 2,237 (4.7%) from two or more races.
Hispanic or
Latino of any race were 8,902 persons (18.6%). 31.8% of the population possessed a bachelor's degree, with 16.4% possessing a Graduate or Professional Degree. The educational attainment level in Rancho Santa Margarita significantly exceeds the averages throughout the rest of California. The Census reported that 47,851 people (100% of the population) lived in households, 2 (0%) lived in non-institutionalized group quarters, and 0 (0%) were institutionalized. There were 16,665 households, out of which 7,699 (46.2%) had children under the age of 18 living in them, 10,144 (60.9%) were
opposite-sex married couples living together, 1,703 (10.2%) had a female householder with no husband present, 700 (4.2%) had a male householder with no wife present. There were 747 (4.5%)
unmarried opposite-sex partnerships, and 103 (0.6%)
same-sex married couples or partnerships. 3,199 households (19.2%) were made up of individuals, and 761 (4.6%) had someone living alone who was 65 years of age or older. The average household size was 2.87. There were 12,547
families (75.3% of all households); the average family size was 3.33. The population was spread out, with 13,879 people (29.0%) under the age of 18, 3,793 people (7.9%) aged 18 to 24, 13,706 people (28.6%) aged 25 to 44, 13,764 people (28.8%) aged 45 to 64, and 2,711 people (5.7%) who were 65 years of age or older. The median age was 36.0 years. For every 100 females, there were 95.6 males. For every 100 females age 18 and over, there were 92.1 males. There were 17,260 housing units at an average density of , of which 11,906 (71.4%) were owner-occupied, and 4,759 (28.6%) were occupied by renters. The homeowner vacancy rate was 1.2%; the rental vacancy rate was 5.6%. 35,737 people (74.7% of the population) lived in owner-occupied housing units and 12,114 people (25.3%) lived in rental housing units.
2009–2013 estimate During 2009–2013, Rancho Santa Margarita had a median household income of $104,113, with 3.9% of the population living below the federal poverty line. ==Government and politics==