Riverdale, CA has a population of 3,964 and is the 7,490th largest city in the United States. The population density is 1,010 per sq mi which is 335% higher than the California average and 1015% higher than the national average. The median age in Riverdale is 29 which is approximately 20% lower than the California average of 36. In Riverdale, 60% of the population over 15 years of age are married, 36% speak English and 63% speak Spanish. 57% of Riverdale residents were born in California, 9% were born out of state, 1% were born outside of the United States and 33% were foreign born.