Part of the New York Enrollment 2026ET series.

SachemET enrolled 14,712 students in 2012. Every year since, it has enrolled fewer. By 2026, the district is down to 11,477, a loss of 3,235 students, 22.0% of its enrollment. Fourteen consecutive years of decline, without a single year of reprieve. SmithtownET has matched that streak exactly: 14 straight years, 3,379 students lost, a 31.8% contraction. These are not small or fragile districts. They are prototypical Long Island suburbs, the kind of places built around their school systems.

Across six of the largest districts in Suffolk County, combined enrollment has fallen from 68,556 in 2012 to 57,799 in 2026. The group has not posted a single year of combined growth in 14 years. And they are not alone. Of 34 major Long Island districts tracked in this analysis, 18 sit at all-time enrollment lows in 2026.

The streaks that will not break

Three Long Island districts hold 14-year unbroken decline streaks, the longest the available district-level series can produce. Sachem and Smithtown get the attention, but NorthportET has lost an even larger share: down 2,088 students, a 33.6% decline, from 6,223 to 4,135. All three peaked in 2012 and have declined every year since.

The trajectories diverge in speed but not direction. Smithtown's losses have been remarkably consistent, averaging 2.7% per year, with no sign of deceleration. Sachem's rate fluctuated, with losses as steep as 482 students in 2013 and as small as 35 in 2025, but the direction never reversed. Northport, the smallest of the three, lost a third of its student body in just over a decade.

What makes these streaks unusual is their persistence through events that elsewhere produced at least temporary enrollment bumps. The 2020-2021 school year, when pandemic disruptions drove families back to suburban districts across the country, produced no relief here. Sachem lost 364 students that year. Smithtown lost 283.

Where the students went

The mechanism behind Long Island's enrollment decline is structural, not episodic. Housing costs on the island have risen sharply, with median residential sale prices in Suffolk County climbing from $563,750 in 2022 to $640,000 in 2024. In Nassau County, the median reached $789,000. Young families who might have once moved to Smithtown or Sachem for the schools now face entry prices that push them to less expensive parts of the state, or out of New York entirely.

The pipeline data in these six districts makes the downstream effect visible. Combined kindergarten enrollment peaked at 4,829 in 2012 and has fallen to 3,840 in 2026, a 20.5% decline. The kindergarten classes entering Sachem and Smithtown today are a fifth smaller than those that entered a decade ago. Those smaller cohorts will flow through to smaller graduating classes by the mid-2030s.

The Empire Center for Public Policy has noted that "Long Island and the counties north of New York City had been slowly losing enrollment prior to the pandemic," a trend that persisted after COVID with little recovery.

The outliers in the room

Not every large Long Island district follows the pattern. William FloydET, in eastern Suffolk County, peaked in 2025 at 9,382 students, growing through the years when its neighbors contracted. BrentwoodET, the largest district on Long Island at 17,295 students, grew from 2012 through 2017, reaching 19,356 before beginning its own decline. Both serve more economically diverse populations than the typical Suffolk suburb.

Brentwood's losses accelerated in 2026, shedding 547 students in a single year, its worst decline since the pandemic year of 2021 (-956). William Floyd posted its first decline in four years, a modest 47 students. Whether these two districts are beginning to follow the pattern their neighbors established years ago, or absorbing a one-year dip, is the open question for the next enrollment cycle.

Eighteen at all-time lows

The 34 major Long Island districts in this analysis range from Brentwood at 17,295 students to Cold Spring HarborET at 1,496. Eighteen of them, more than half, are at their all-time enrollment low in 2026. The losses from peak are steepest in HempsteadET, down 42.0% from 8,040 (2017) to 4,665. Northport has lost 33.6%, Smithtown 31.8%, West IslipET 28.1%, and Half Hollow HillsET 27.1%.

CommackET, which appeared destined for its own 14-year streak, managed a gain of three students in 2026 to break the run. The district still sits at 5,402, down 27.0% from its 2012 peak of 7,399. Three students is not a recovery.

Year-over-year: a pattern of steady erosion

The combined year-over-year chart for the six focus districts tells a story of relentlessness. Every bar is red. The worst years were 2021 (-1,949, driven by COVID) and 2019 (-1,518, pre-pandemic). Even the "best" years, 2023 (-67) and 2025 (-103), were losses. The 2026 drop of 1,016 students marks a return to the steeper pace of decline after two years of relative stability.

New York's Foundation Aid formula continues to direct $24.9 billion to school districts statewide, and a "save harmless" provision ensures that no district's aid drops below its prior-year level regardless of enrollment. For Long Island districts losing hundreds of students per year, this provision acts as a fiscal cushion, maintaining funding levels even as the students the funding is designed to serve move elsewhere. The question is how long that cushion holds.

What to watch

The kindergarten pipeline offers the clearest forecast. Combined K enrollment across these six districts hit its lowest point on record in 2026, at 3,840. That cohort will progress through the system for the next 12 years, guaranteeing smaller class sizes at every grade level it passes through. For Sachem and Smithtown, the question is no longer whether the decline continues. Fourteen years of unbroken losses have answered that. The question is whether the pace accelerates as the pipeline's smallest-ever cohorts reach middle school and high school.

Commack broke its streak in 2026 by three students. That was enough to stop the count. It was not enough to change anything about a district that has lost 27% of its enrollment since 2012. Brentwood, which grew while its neighbors shrank, posted its third-worst year on record in 2026, losing 547 students. Suffolk County median home prices climbed to $640,000 in 2024. The young families who once bought starter homes in Smithtown and Sachem for the school system are buying elsewhere, or not buying at all. The houses remain. The children do not.

Detailed code that reproduces the analysis and figures in this article is available exclusively to EdTribune subscribers.