Walnut Grove, CA has a population of 1,469 and is the 12,815th largest city in the United States. The population density is 144 per sq mi which is 38% lower than the California average and 59% higher than the national average. The median age in Walnut Grove is 46 which is approximately 28% higher than the California average of 36. In Walnut Grove, 68% of the population over 15 years of age are married, 67% speak English and 30% speak Spanish. 72% of Walnut Grove residents were born in California, 13% were born out of state, 0% were born outside of the United States and 15% were foreign born.