Round Valley, CA has a population of 461 and is the 20,037th largest city in the United States. The population density is 33 per sq mi which is 86% lower than the California average and 63% lower than the national average. The median age in Round Valley is 41 which is approximately 13% higher than the California average of 36. In Round Valley, 35% of the population over 15 years of age are married, 79% speak English and 17% speak Spanish. 64% of Round Valley residents were born in California, 21% were born out of state, 4% were born outside of the United States and 11% were foreign born.