Mercer Island Population

1960–2026

25,250

2026 projection

1.9% since 2020 (decrease)

05K10K15K20K25K30K1960197019801990200020102020

Source: U.S. Census Bureau decennial counts and annual estimates, including 2010–2020 intercensal estimates. 2026 is a projection. Values between recorded years are interpolated.

Use the left and right arrow keys to inspect population observations.

Population by year

Population estimates for Mercer Island. Annual change is shown as a percentage. Growth is the total change since the preceding observation.
202625,250-1720.68%
202525,422+3641.45%
202425,058+1470.59%
202324,911-1290.52%
202225,040-2951.16%
202125,335-4131.60%
202025,748+270.10%
201925,721-460.18%
201825,767+1340.52%
201725,633+1160.45%

Showing 10 of 22 years.

The 2020 row compares the April 1 Census count with the July 1, 2019 estimate (about nine months). Its Growth and Annual change therefore do not represent a full year.

Growth since 2020, compared

Mercer Island has a population change lower than King County, Washington, and the U.S.

  • Washington+3.5%
  • King County+3.1%
  • United States+3.1%
  • Mercer Island−1.3%

Change from July 1, 2020 to July 1, 2025 population estimates—not annualized growth or site projections.

Source: U.S. Census Bureau. U.S. totals are summed from the 50 states and D.C.; unavailable comparisons are omitted.

Mercer Island Demographics

46.4median age

Median age

Female46.9 yrs
Male45.7 yrs

Adults

19,873
5,610 seniors (65+) · 28% of adults14,263 other adults

Sex

Female 52.4% · 13,251Male 47.6% · 12,056

Population by age

MaleFemale85+ years, male: 51485+ years, female: 71980–84 years, male: 35680–84 years, female: 32475–79 years, male: 52775–79 years, female: 49570–74 years, male: 51070–74 years, female: 75265–69 years, male: 77865–69 years, female: 63560–64 years, male: 68860–64 years, female: 1,17955–59 years, male: 84655–59 years, female: 82150–54 years, male: 1,12650–54 years, female: 1,12045–49 years, male: 78045–49 years, female: 91340–44 years, male: 73340–44 years, female: 85535–39 years, male: 57035–39 years, female: 85130–34 years, male: 58130–34 years, female: 48525–29 years, male: 49425–29 years, female: 57820–24 years, male: 51520–24 years, female: 47615–19 years, male: 1,14915–19 years, female: 94010–14 years, male: 71310–14 years, female: 8655–9 years, male: 8015–9 years, female: 7710–4 years, male: 3750–4 years, female: 47285+80–8475–7970–7465–6960–6455–5950–5445–4940–4435–3930–3425–2920–2415–1910–145–90–45005001K1K

Hover or tap an age group to see exact counts. Use the up and down arrow keys to inspect age groups.

U.S. Census Bureau, 2024 ACS 5-year estimates · Table S0101

Race and ethnicity

Tap a square or a group below to highlight it.

Each square is about 1% of residents (roughly 253 people).

Hispanic or Latino residents can be of any race. All other groups exclude Hispanic residents.

U.S. Census Bureau, 2024 ACS 5-year estimates · Table B03002

Mercer Island Income

$219,069median household income

Median household income

$219,069

Half of households earn more, half earn less

Median earnings

$130,625

Typical yearly pay for a worker 25 or older.

Poverty rate

3.8%

About 1 in 26 residents

U.S. Census Bureau, 2024 ACS 5-year estimates · Tables S1901, S1501, S1701

Mercer Island Marital Status

63% of residents age 15 and older are married.

MarriedNever married
Overall
Male
Female
Marital status of residents age 15 and older
StatusOverallMaleFemale
Married63%66%60%
Never married24%27%22%
Divorced7%4%9%
Widowed6%3%8%
Separated<1%<1%<1%

U.S. Census Bureau, 2024 ACS 5-year estimates · Table S1201

Sources

14 sources

Population

American Community Survey, 2024 5-year

Additional sources