Mercer Island, WA Profile: Facts, Map & Data


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Mercer Island, Washington - Basic Facts

The City of Mercer Island had a population of 24,720 as of July 1, 2017. Mercer Island ranks in the upper quartile for Population Density when compared to the other cities, towns and Census Designated Places (CDPs) in Washington. See peer rankings below.

The primary coordinate point for Mercer Island is located at latitude 47.5627 and longitude -122.2257 in King County. The formal boundaries for the City of Mercer Island (see map below) encompass a land area of 6.32 sq. miles and a water area of 0 sq. miles. King County is in the Pacific time zone (GMT -8). The elevation is 335 feet.

The City of Mercer Island (GNIS ID: 2411082) has a C1 Census Class Code which indicates an active incorporated place that does not serve as a county subdivision equivalent. It also has a Functional Status Code of "A" which identifies an active government providing primary general-purpose functions.

Washington is one of 20 states where Census County Divisions (CCDs) are used for statistical tracking of subdivisions within each county. The City of Mercer Island is located within Seattle East Division of King County.

Beneath the boundary map are tables with Mercer Island population, income and housing data, five-year growth projections and peer comparisons for key demographic data. The estimates are for July 1, 2017.

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City of Mercer Island, WA Boundary Map

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Mercer Island, WA Data & Demographics (As of July 1, 2017)


Total Population 24,720
Daytime Population: Workers 7,503
Daytime Population: Residents 13,555
Total Daytime Population (TDP) 21,058
Ratio TDP/Total Population1 0.85
Population in Households 24,720
Population in Familes 21,081
Population in Group Qrtrs 0
Population Density2 3,911
Diversity Index3 46


Median Household Income $139,623
Average Household Income $206,648
Per Capita Income $82,710


Total Housing Units 10,605 (100%)
Owner Occupied HU 7,012 (66.1%)
Renter Occupied HU 2,882 (27.2%)
Vacant Housing Units 711 ( 6.7%)
Median Home Value $1,000,001
Average Home Value $1,008,439


Total Households 9,894
Average Household Size 2.5
Family Households 7,080
Average Family Size 3
  1. If the ratio of the TDP to Total Population is greater than 1, the location gains population during the day when commuting workers are present. If the ratio is less than 1, the location is more of a bedroom community where people commute to another place for work.
  2. Population Density = Total Population per square mile.
  3. The Diversity Index is a scale of 0 to 100 that represents the likelihood that two persons, chosen at random from the same area, belong to different race or ethnic groups. If an area's entire population belongs to one race AND one ethnic group, then the area has zero diversity. An area's diversity index increases to 100 when the population is evenly divided into two or more race/ethnic groups.


2010-2017 2017-2022
Population 1.18% 1.2%
Households 1.15% 1.14%
Families 1.12% 1.13%
Median Household Income   0.79%
Per Capita Income   1.34%

Mercer Island, WA - Peer Comparisons by Rank and Percentile

The table below compares Mercer Island to the other 627 incorporated cities, towns and CDPs in Washington by rank and percentile using July 1, 2017 data. The location Ranked # 1 has the highest value. A location that ranks higher than 75% of its peers would be in the 75th percentile of the peer group.

Variable Description Rank Percentile
Total Population # 46 93rd
Population Density # 42 93rd
Diversity Index # 217 65th
Median Household Income # 8 99th
Per Capita Income # 5 99th

Additional comparisons and rankings can be made with a VERY EASY TO USE Washington Census Data Comparison Tool.

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