Rio Vista, CA has a population of 8,055 and is the 4,658th largest city in the United States. The population density is 1,214 per sq mi which is 422% higher than the California average and 1240% higher than the national average. The median age in Rio Vista is 62 which is approximately 73% higher than the California average of 36. In Rio Vista, 68% of the population over 15 years of age are married, 86% speak English and 5% speak Spanish. 51% of Rio Vista residents were born in California, 36% were born out of state, 2% were born outside of the United States and 11% were foreign born.