Data changelog
What changed, and when
Zoning data decays quietly: a page that was right in 2024 looks exactly like a page that is right today. This is the record of every change to the data behind this site and to what the site claims about it — sources read, coverage added, and corrections made. Last change: 25 August 2026.
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Corrected the zoning verification letter contact in the report
The manual-diligence checklist at the end of every parcel report sent readers to Room 1000 at 121 N LaSalle St on (312) 744-5772 for a zoning verification letter. Both were wrong: Room 1000 is the Department of Planning & Development’s general floor, while requests and payment go to the Bureau of Zoning in Room 905, and the published number is (312) 744-5777. Anyone following it would have mailed their request and cheque to the wrong room. Verified against the City’s own Office of the Zoning Administrator page, which also gives the figures we had omitted: a $150 filing fee, one zoning lot per request, and up to 30 days for issuance. Those now appear in the report and on the site.
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Removed a minimum lot area that does not exist in the B and C districts
All 25 business and commercial district pages showed “Minimum lot area: 2,500 sq ft”. Chapter 17-3 establishes no minimum lot area for B and C districts — bulk there is governed by floor area ratio and lot area per unit — and the figure carried no ordinance citation on any of the 25. It appears to have been copied from the dash-1 lot-area-per-unit standard. The row is gone, and the spec sheet now refuses to render any figure that has no verification record, so this class of error cannot recur silently.
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Residential, business and commercial bulk figures re-checked against edition 2026-S-73
The 35 R, B and C districts were read in 2024 from a third-party report excerpt, the oldest source on this site. Their bulk standards — floor area ratio, lot area per unit, building height and minimum lot area — have now been compared field by field against the current adopted edition 2026-S-73. All matched; no figure changed. Setbacks and parking ratios were not part of this pass and still rest on the 2024 reading, which the district pages say.
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Per-district provenance replaces a single sitewide claim
Every district page had carried one hardcoded line — "source excerpts dated 2024-09-18" — which flattened three different verification sources into the oldest of them, understating the downtown and manufacturing districts by roughly two years. Each district page now states the source and date its own figures were read from, and the methodology page prints the full breakdown. No figures changed; what changed is that we now say where each one came from.
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Authorship, methodology and limitations published
Added /about, /methodology and /methodology/coverage. The site had been publishing 3,918 district rows with no author, no contact address and no statement of provenance. The coverage page names the 21 city guides that carry no district roster, keeping Houston — which genuinely has no conventional zoning — separate from the 20 that are gaps in our data.
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City layer: 327 guides, 3,918 districts
Added a national /zoning hub and city guides for 327 cities. Rosters were drafted from each city’s ordinance, then checked against that city’s published zoning GIS layer — the district codes actually painted on the official map. Where the two disagreed, the map won.
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All 50 states
Added /coverage and a page per state covering who holds the zoning power, under which enabling statute, and the recent reforms that override local rules. Fact-checking against statute text removed several confidently-worded citations to acts that do not exist.
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Chicago reference published
First publication: 53 Chicago base districts with bulk standards cited field by field to Title 17, plus explainers on Connected Communities, ADUs and coach houses, and the Affordable Requirements Ordinance. The data snapshot behind these pages was generated on this date.
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Manufacturing districts read from the current adopted edition
The nine M districts were read from Title 17, chapter 17-5, in edition 2026-S-73 — the current adopted edition, and the strongest provenance on the site.
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Downtown districts read from the City-published text
The nine D districts were read from the City-published text of Title 17, chapter 17-4.
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Residential, business and commercial districts read
The 35 R, B and C districts were read from a Title 17 excerpt contained in a third-party zoning report of this date — the oldest source on this site. Their bulk figures were re-checked against the current adopted edition on 24 August 2026 and found unchanged; setbacks and parking ratios still rest on this reading.
What counts as an entry
Changes to the data, or to what the site claims about it. Not deploys, not copy edits. If a figure changed, or the source behind a figure changed, or we found something wrong and narrowed a claim, it is here.
Found something we should have logged — or something still wrong? Email team@realdevelop.io. Corrections get an entry of their own, including the ones that make us look worse. How the data is produced →