Best High Schools in Zip Code 98040

ZIP code 98040 has one listed high school, Mercer Island High School, serving grades 9–12 with 1,439 students in the suburban Mercer Island area. Because there is only one high school in the ZIP code, parents cannot compare several local high schools directly; instead, the school’s results are best understood by comparing them with the Mercer Island School District, Washington averages, and the school’s recent performance.

Mercer Island High School is consistently one of Washington’s highest-performing schools. It ranked second statewide in 2025–26, fourth in 2024–25, and third in 2023–24, placing at the 99th percentile in each year. In 2025–26, 92.71% of students were proficient in English language arts, 79.81% in math, and 88.59% in science. These results were about 37 to 40 percentage points higher than statewide averages. The school also exceeded district results in English language arts and science, while its math rate was slightly below the district’s 81.14%.

Graduation and student persistence are also major strengths. The 2024–25 graduation rate was 96.1%, matching the district and standing 13.5 percentage points above Washington’s 82.6% rate. The dropout rate was just 1.3%, compared with 9.8% statewide. Academic results declined modestly from the prior year, particularly in science, but remained excellent overall. Math is the clearest area to monitor because it trails the school’s English and science results and is slightly below the district, even though it remains far above the state average. The school reports a student-teacher ratio of 18.8 to 1 and per-student spending of $19,890.