South Monrovia Island, CA has a population of 6,779 and is the 5,290th largest city in the United States. The population density is 12,359 per sq mi which is 5218% higher than the California average and 13541% higher than the national average. The median age in South Monrovia Island is 36 which is approximately 1% lower than the California average of 36. In South Monrovia Island, 48% of the population over 15 years of age are married, 31% speak English and 61% speak Spanish. 59% of South Monrovia Island residents were born in California, 7% were born out of state, 0% were born outside of the United States and 34% were foreign born.