Watertown, NY has a population of 26,997 and is the 1,603rd largest city in the United States. The population density is 2,989 per sq mi which is 733% higher than the New York average and 3199% higher than the national average. The median age in Watertown is 31 which is approximately 19% lower than the New York average of 38. In Watertown, 53% of the population over 15 years of age are married, 93% speak English and 5% speak Spanish. 71% of Watertown residents were born in New York, 22% were born out of state, 3% were born outside of the United States and 4% were foreign born.