🇺🇸 United States ZIP Code

STANDARD

98040

Mercer Island

ZIP Code 98040 is a standard zip code serving Mercer Island, Mercer Island, Washington (WA), in King County, United States. It has an estimated population of 22,699 with a median household income of $126,359. The area falls within the America/Los_Angeles timezone.

Median Household Income vs. National Average

Location

Country: 🇺🇸 United States
State / Province: Washington (WA)
County: King
City: Mercer Island
Timezone: America/Los_Angeles

Coordinates

Latitude: 47.560300
Longitude: -122.228100

Geographic Details

Land Area: 6.32 mi²
Water Area: 6.79 mi²
Population Density: 3591.0 people per mi² (90th percentile)
Bounding Box: 47.613620°N, 47.518421°S, -122.199007°E, -122.268160°W

With 22,699 residents spread across 6.32 square miles, this area has a population density of 3591.0 people per square mile.

Demographics

22,699

Population

80th percentile

$126,359

Median Income

95th percentile

$864,000

Median Home Value

95th percentile

6.32 mi²

Land Area

The median household income in 98040 is $126,359, and the median home value is $864,000. This places the area in the top 25% nationally for household income.

Housing

9,930

Total Units

9,109

Occupied Units

91.7%

Occupancy Rate

Similar ZIP Codes in Washington

ZIP codes with similar median household income in Washington.

98074

Sammamish

$143,686

98296

Snohomish

$109,355

98075

Sammamish

$142,926

98053

Redmond

$116,518

98006

Bellevue

$110,290

98077

Woodinville

$137,125

98065

Snoqualmie

$121,415

98072

Woodinville

$107,654

Frequently Asked Questions

What information is available for each ZIP code?

Each ZIP code page shows city, state, county, geographic coordinates, timezone, population, median household income, median home value, housing units, land area, population density, commute time, educational attainment, area codes, and ZIP code type (Standard, PO Box, or Unique).

What are the different types of ZIP codes?

There are three types of ZIP codes: Standard (residential and commercial delivery areas), PO Box (assigned to post office box sections), and Unique (assigned to a single high-volume address like a government agency or large company). Standard ZIP codes are the most common.

How often is ZIP code data updated?

ZIP code assignments are updated quarterly by the USPS. Demographic data comes from the US Census Bureau's American Community Survey (ACS), which releases new 5-year estimates annually. ZipFYI updates its data to reflect the latest available information.

What is population density and why does it matter?

Population density measures the number of people per square mile in a ZIP code area. It helps identify urban vs. rural areas, affects real estate values, impacts service availability, and is used in market analysis. Dense urban ZIP codes may have 50,000+ people per square mile.

How are ZIP code boundaries determined?

ZIP code boundaries are determined by the USPS based on mail delivery routes, not political or geographic boundaries. They follow carrier routes and may cross city, county, or even state lines. Boundaries can change when the USPS reorganizes delivery operations.

What does median household income tell me about a ZIP code?

Median household income is the middle value when all household incomes in a ZIP code are sorted. Half of households earn more and half earn less. It is a better indicator of typical earnings than average income, which can be skewed by very high or very low outliers.