Watertown, FL has a population of 3,451 and is the 8,116th largest city in the United States. The population density is 1,440 per sq mi which is 251% higher than the Florida average and 1490% higher than the national average. The median age in Watertown is 36 which is approximately 13% lower than the Florida average of 42. In Watertown, 52% of the population over 15 years of age are married, 96% speak English and 1% speak Spanish. 53% of Watertown residents were born in Florida, 45% were born out of state, 1% were born outside of the United States and 1% were foreign born.