From a total population of 20,488, Watertown has a median age of 36.8. The average age of males, in Watertown, is 35.3 while the average age of females is 38.5. When you compare this to median age of South Dakota, Watertown is roughly the same.
The median income of individuals, in Watertown, is $25,185 while the average household income is $45,185. When comparing the median income of people living in Watertown to the rest of South Dakota, the average income in Watertown is $1,126 less.