Keystone Heights, FL has a population of 1,530 and is the 12,572nd largest city in the United States. The population density is 1,391 per sq mi which is 374% higher than the Florida average and 1435% higher than the national average. The median age in Keystone Heights is 37 which is approximately 11% lower than the Florida average of 42. In Keystone Heights, 61% of the population over 15 years of age are married, 96% speak English and 2% speak Spanish. 57% of Keystone Heights residents were born in Florida, 38% were born out of state, 2% were born outside of the United States and 4% were foreign born.