South El Monte, CA has a population of 20,566 and is the 2,108th largest city in the United States. The population density is 7,233 per sq mi which is 3013% higher than the California average and 7884% higher than the national average. The median age in South El Monte is 34 which is approximately 5% lower than the California average of 36. In South El Monte, 49% of the population over 15 years of age are married, 17% speak English and 69% speak Spanish. 52% of South El Monte residents were born in California, 4% were born out of state, 1% were born outside of the United States and 43% were foreign born.