Alto, CA has a population of 649 and is the 17,927th largest city in the United States. The population density is 5,161 per sq mi which is 2121% higher than the California average and 5597% higher than the national average. The median age in Alto is 53 which is approximately 47% higher than the California average of 36. In Alto, 70% of the population over 15 years of age are married, 72% speak English and 21% speak Spanish. 60% of Alto residents were born in California, 16% were born out of state, 0% were born outside of the United States and 24% were foreign born.