From a total population of 24,163, Mercer Island has a median age of 45.5. The average age of males, in Mercer Island, is 44.9 while the average age of females is 46. When you compare this to median age of Washington, Mercer Island is 8.1 years older.
The median income of individuals, in Mercer Island, is $75,396 while the average household income is $125,651. When comparing the median income of people living in Mercer Island to the rest of Washington, the average income in Mercer Island is $44,163 more.