Palo Alto, CA has a population of 66,649 and is the 558th largest city in the United States. The population density is 2,793 per sq mi which is 1102% higher than the California average and 2982% higher than the national average. The median age in Palo Alto is 42 which is approximately 16% higher than the California average of 36. In Palo Alto, 64% of the population over 15 years of age are married, 60% speak English and 6% speak Spanish. 35% of Palo Alto residents were born in California, 28% were born out of state, 2% were born outside of the United States and 34% were foreign born.