Aliso Viejo, CA has a population of 50,219 and is the 813th largest city in the United States. The population density is 7,258 per sq mi which is 3023% higher than the California average and 7911% higher than the national average. The median age in Aliso Viejo is 37 which is approximately 1% higher than the California average of 36. In Aliso Viejo, 59% of the population over 15 years of age are married, 72% speak English and 9% speak Spanish. 54% of Aliso Viejo residents were born in California, 23% were born out of state, 2% were born outside of the United States and 21% were foreign born.