Jacksonville, FL has a population of 856,616 and is the 12th largest city in the United States. The population density is 1,146 per sq mi which is 290% higher than the Florida average and 1165% higher than the national average. The median age in Jacksonville is 36 which is approximately 14% lower than the Florida average of 42. In Jacksonville, 50% of the population over 15 years of age are married, 86% speak English and 6% speak Spanish. 50% of Jacksonville residents were born in Florida, 37% were born out of state, 3% were born outside of the United States and 10% were foreign born.