Walnut, CA has a population of 30,026 and is the 1,429th largest city in the United States. The population density is 3,339 per sq mi which is 1337% higher than the California average and 3585% higher than the national average. The median age in Walnut is 44 which is approximately 22% higher than the California average of 36. In Walnut, 65% of the population over 15 years of age are married, 35% speak English and 13% speak Spanish. 41% of Walnut residents were born in California, 8% were born out of state, 2% were born outside of the United States and 50% were foreign born.