MassPermits publishes analysis without a byline, so the only thing worth trusting is the method. This page describes it in enough detail that a stranger could re-run any figure on the site and get the same answer.
37,361 building-permit records from 31 Massachusetts municipal sources, each one publishing its own records. The dataset behind this build was assembled 2026-08-18 and spans 2026-02-19 to 2026-08-18.
Every record originates with the municipality that issued it, published by that town in its own format - spreadsheets, monthly PDFs, and open-data portals. The full list, with record counts and date spans, is on the coverage page.
20 of 31 sources publish no declared project value. 11 publish a category label instead of a description of the work. 2 publish coordinates. Each absence rules out a class of question, and the affected sources are excluded from those questions by name rather than silently averaged in.
The trade on every page of this site - Roofing, HVAC, Electrical and the rest - is derived by us from what the town published, not a field the town provides. Where a town publishes a category label we use it; otherwise the description text is matched against rules. Classification error is therefore our error, not the municipality's, and each research article prints the exact rule it used.
Coverage differs enormously from town to town, so comparing raw counts between towns measures our pipeline rather than Massachusetts.
Some towns file a whole category of work under a fixed label instead of a description. Searching their text finds one side of a comparison and not the other, which produces a confident and completely false number. Those sources are named and excluded, not ranked.
The contractor column is never article subject matter at any level of aggregation, because most of its values are private people.
If a figure moves outside the range its sentence was written for, the page stops rendering rather than publish a claim its own data no longer supports.
Public pages and feeds mask the house number of every address and never publish an owner name. The contractor field is withheld from every public page - most of its values are private individuals rather than firms, so it is treated as personal data and is never the subject of an article. Full details are supplied only to paying subscribers, under the terms they agree to.
Corrections are appended, never silently edited, and a corrected article keeps its URL. The corrections page also records analyses that were completed and then rejected before publication, with the reason.
Figures and tables on this site are published under CC BY-NC 4.0. Attribution to MassPermits, non-commercial reuse.
Each research article links a JSON file containing every number on the page plus the rules and thresholds used to produce it. Beyond that: the open-data catalog, the JSON feed, and RSS, with per-town CSV, JSON and XML linked from every town page.
Exact addresses, contractor & owner details, and a sortable file — plus a free sample so you can see the quality first.
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