Each year at this time the trade magazine School Planning and Management publishes a survey of recent public-education construction, regional and national, complete with median and average square footages per pupil at the elementary, middle, and high school levels.
Historically, public education has used state sid for educational construction as the lever for compliance with State regulation of school construction, which has long used square-footage-per pupil-in-the-classroom as one of many building design criteria.
For decades that magic number has been 30 in most states, even as other requirements like minimum classroom size in Vermont, the ratio of plumbing fixtures to enrollment, the intensity of lighting and ventilation, and so on, have come and gone, varied from state-to-state (different student bladder capacities, no doubt) or been adjusted up and down as energy has cycled up and down in cost. In almost all States, total square footage per pupil (SF/P) at the elementary, middle, and high school levels has been remarkably constant over those same decades.
Vermont has been one recent exception, and there may be others; Michigan, for example, where large school districts like Detroit have been plunging in enrollment even faster, and are not only putting fewer students in individual classrooms (like Vermont) but have been closing schools (unlike Vermont) as enrollment declines.
Now the SP&M numbers are out again, and again New England, including Vermont, is posting much higher numbers than the rest of the country. A little educational history is enlightening.
In the Roaring Twenties, for example, when the now-well-known inner rings of suburbs around American cities -places such as Brookline in Massachusetts and Oak Park in Illinois-were being built and expanded, many public high schools of that era were designed with a substantial percentage of what today would be considered under-sized classrooms, half the typical 900 sq. ft., so that administrators could improve student achievement via half-size classes: not 30 or so, but more like 15.