Mercer Island is a city located in King County Washington. With a 2020 population of 25,918, it is the 43rd largest city in Washington and the 1490th largest city in the United States . Mercer Island is currently growing at a rate of 0.05% annually and its population has increased by 14.18% since the most recent census, which recorded a population of 22,699 in 2010. Mercer Island reached it's highest population of 25,918 in 2021. Spanning over 13 miles, Mercer Island has a population density of 4,061 people per square mile.
The average household income in Mercer Island is $224,619 with a poverty rate of 5.59%. The median rental costs in recent years comes to $2,162 per month, and the median house value is $1.22 Mn. The median age in Mercer Island is 46 years, 45.2 years for males, and 46.4 years for females.