Mercer Island, WA population, income and ZIP codes

Mercer Island city is a small city in Washington, with 25,282 residents counted in the Census American Community Survey 2019-2023 ACS 5-year estimates, which places it #51 of 639 ranked by population — larger than 92% of them. The median age here is 45.8 years against 39.1 nationally, a markedly older profile that usually tracks retirees staying put and younger households leaving for work. Places under 65,000 residents only appear in the five-year release, never the one-year file, so these values pool sixty months of responses and lag the current year by design.

Households in Mercer Island city earn a median of $202,359 a year, 157.7% above the national figure of $78,538 and 123% above the $90,592 median for the 393 Washington cities we cover. The median is the midpoint household, not an average, so a handful of very high earners cannot drag it upward the way they distort a mean. Poverty reaches 4.6% of residents here, less than half the 12.4% national rate.

The typical owner-occupied home in Mercer Island city is valued at $1,884,200, 521% above the national figure and 302% above the $468,400 peer median, while median gross rent runs $2,464 a month, 75.2% above the national figure, or roughly $29,568 across a full year. A household on the local median income would put about 14.6% of gross pay toward that rent against the federal 30% cost-burden threshold, so renting here is cheap relative to what people here earn. The home-price-to-income ratio works out to 9.3×, against roughly 3.9× nationally, so buying is out of reach on local earnings alone and the ownership market leans on outside income, equity or dual high earners. 66% of occupied homes are owner-occupied versus 65% nationally, so the market leans toward owners. Gross rent folds in the utilities a tenant pays separately, so it is closer to the real monthly outlay than a headline rent figure.

Home values sit at 9.3× median household income, far past the 3.9× national mark, so ownership costs here are set by something other than local wages — second homes, retirees with equity, or commuters earning elsewhere.

No figure on this page is estimated by us; each one comes straight from the published ACS tables for this area. Small-area estimates still carry wider margins of error than state or national figures, so check the linked ACS tables before relying on them for lending, appraisal or legal work.