NYC DOE ran high schools like the residency match

Every eighth-grader applying to a New York City public high school listed five preferred schools and hoped for the best; schools made offers directly, with no coordination between them, and a student could hold multiple offers while others held none. The congestion this created was the visible failure: nearly half of students ended up assigned to a school that wasn't even on their five-school list, sent through an unpopular administrative placement instead.

In 2003-04, economists Atila Abdulkadiroğlu, Parag Pathak and Alvin Roth — extending the same deferred-acceptance matching theory behind the medical residency Match — redesigned the process for New York City students entering high school in September 2004: one round, ranked preferences submitted once, computed centrally instead of negotiated school by school.

Replaced the strategic high-school application scramble with a deferred-acceptance match designed by the same economists.

Imported the residency match's deferred-acceptance algorithm, cutting unmatched students from thirty thousand to three thousand in one year.

Deferred acceptance centralizes offers, so no student holds multiple while others hold none.

The algorithm was already proven stable and strategy-proof in the residency match.

Adapting existing math meant no need to invent or validate a new mechanism.

Unmatched students fell from 30k to 3k in the first year.

When a process has the same structure as one already solved, transplant the proven mechanism instead of patching the old one.

Students left unassigned by the process fell from roughly thirty thousand to three thousand in the first year. That 31,000-to-3,000 drop is why the NYC redesign stands alongside the residency Match and kidney exchange as one of matching theory's three flagship applications. Boston adopted a comparable redesign for its own school-choice system in 2006, using the same team's research on the trade-offs between strategy-proofness and efficiency.