Summary:
The two high schools in Riverdale Joint Unified serve grades 7–12: Riverdale High serves grades 9–12 and enrolls 496 students, while Horizon High serves grades 7–12 and enrolls 7; together, they serve 503 students. Horizon’s school-level proficiency results are suppressed, and its graduation and dropout rates were not reported, so those outcomes cannot be compared directly between the schools. Riverdale’s clearest academic strength is ELA: 50% proficiency, about level with the state’s 49%; its math result is 17% versus 38% statewide, and science is 21% versus 36%—making the sharp subject gap the key academic takeaway.
Riverdale High stands out for school completion: its graduation rate was 97%, 9 percentage points above the state’s 88%, and its dropout rate was 0%, 8 points below the state’s 8%. The most striking school-to-school difference is attendance: chronic absenteeism was 81% at Horizon High and 13% at Riverdale, a 68-point gap. Horizon’s rate was also 63 points above the state’s 18%, while Riverdale’s was 6 points below it. These figures make Horizon the clear outlier for absenteeism, while Riverdale combines stronger attendance and completion results with uneven academic proficiency.
Riverdale’s subject trends are mixed: from 2024–2025 to 2025–2026, its ELA proficiency rose from 46% to 50%, moving from 2 points below the state to essentially level; math fell from 20% to 17%, widening its state gap from 17 to 22 points, and science rose from 20% to 21% as its gap widened from 12 to 15 points. SchoolDigger’s Riverdale percentile also declined, from 55th in 2023–2024 to 39th in 2025–2026, a 16-point drop; Horizon’s listed percentiles are from separated earlier years. As context, Riverdale’s free/reduced lunch eligible measure was 91% in 2024–2025, compared with 86% at Horizon in 2023–2024; the schools also had student-teacher ratios of 15.1 and 3.5, respectively.
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