Suffolk County, Massachusetts property research

Official MassGIS snapshot retrieved 2026-09-23. Assessment fiscal year is retained per record and varies by municipality; retrieval does not certify current ownership. Snapshot parcel_id contains source OBJECTID and is not a persistent cross-vintage identifier. Town, assessment-property, LOC_ID and map-parcel identifiers are retained for reviewed joins.

Attribution: MassGIS (Bureau of Geographic Information), Commonwealth of Massachusetts EOTSS; originating municipal assessors
Source: https://www.mass.gov/info-details/massgis-data-property-tax-parcels
Reuse: MassGIS states publicly funded data are in the public domain and may be used for any purpose.
https://www.mass.gov/info-details/massgis-frequently-asked-questions

These are dated research files, curated from public source facts. Ownership is an assessor entry, not verified legal title or a statement that a property is for sale. Source and import dates differ; September 2026 enrichment does not refresh the underlying assessment or ownership record.

GEOGRAPHY: Every retained valid parcel's representative point is tested against the official Census ACS 2024 county boundary with a 100-meter boundary tolerance. Valid source geometry is preserved. Where explicitly documented in GEOMETRY RECOVERY below, exact duplicate rings may be removed with the original geometry retained as evidence. Unrecoverable geometry receives null analytical results. Parcel record count describes the imported selection, not a guarantee of all current parcels. Distinct identifiers are retained even when geometries overlap (for example condominium interests).

FLOOD: Full valid parcel polygons intersect official FEMA NFHL flood-hazard polygons. Union areas avoid double counting; intersections smaller than one square meter are omitted. Percentages use the full parcel area as denominator, with coverage recorded separately. Special Flood Hazard Area means SFHA_TF=T. Coverage below 99.9% leaves an unknown remainder, not a negative flood finding. Zone X and zero mapped SFHA do not certify freedom from flooding. This is screening data, not a flood certificate, survey, insurance recommendation or engineering opinion.

SCHOOLS: NCES 2024-25 physical active public-school points and Census ACS 2024 unified-school districts. Nearest school is shortest parcel-to-point straight-line distance among retrieved physical schools in the state. It does not determine attendance eligibility, walking distance or school quality. Verify enrollment with the district.

ZONING: Where present, zoning is copied from an original assessor attribute. No contemporary zoning-polygon overlay or permitted-use verification is performed for this pack. Blank means unavailable. Land use is the original tax classification, not a permitted-use conclusion. Utility service/capacity, development approval, road access, title and survey boundaries are not established by these files.

DATA HANDLING: Zero remains distinct from missing. Blank, UNKNOWN and punctuation-only address placeholders become null. Original source field names and dates are documented. Texas date_acq is acquisition date, NEVER treated as sale date. Invalid source parcel geometry is not silently repaired; invalid overlay geometries may be repaired for intersection and counts are documented. Owner names and public tax mailing addresses only; no personal phone/email enrichment or demographic profiling.

USAGE: Paid curation of nonexclusive public facts; internal business and client work are allowed. Attribution is retained. LandSight claims no exclusive rights to government facts. Seven-day correction/refund policy if delivered files fail their stated scope: dakota@landsightsolutions.com.

FEMA SOURCE VINTAGE: This pack uses the complete official Massachusetts NFHL_25_20260910 state database. Latest study effective date 2026-06-23; latest LOMR effective date 2026-09-11. Complete polygons are selected without clipping or simplification. Native NAD83 coordinates are converted using NAD_1983_To_WGS_1984_5 (Esri WKID1515, published accuracy 1 metre). Provenance includes the archive checksum, transformation, full-row reconciliation and independent live-source identity/geometry controls. Archive row IDs differ from live REST IDs. Retrieval does not imply changes after this archive vintage are included.

Projection for measured areas/distances: EPSG:26919
COUNTY BOUNDARY REVIEW: Of 208,740 retrieved source records, 208,724 are in the main parcel file. Sixteen source records whose representative points lie outside the official county boundary plus 100 metres are preserved in excluded-source-records.json, with their original attributes/geometry and a measured review queue. All 16 have zero area within that county boundary and missing source assessment year. These are unresolved source-location records, not silently discarded parcels or corrected county assignments.


NATIONAL WETLANDS INVENTORY SCREENING
Source: U.S. Fish and Wildlife Service, National Wetlands Inventory, May 2026 state download. Imagery years vary and are retained per parcel; the download release or retrieval date is NOT the imagery date. NWI maps wetland and deepwater habitat using biological definitions. Mapping does not establish regulatory jurisdiction or show every wetland. No mapped overlap is not a certification that wetlands are absent.
Full valid parcel polygons are intersected with NWI polygons in their native equal-area EPSG:5070 projection. Overlap uses the union of intersections of at least one square metre. Original parcel geometry and all prior fields are preserved. Invalid parcel geometry remains analytically unknown. Project coverage is limited to the official state download footprint. Parcels extending beyond the retrieval extent are marked unknown.
nwi-evidence.ndjson retains matched NWI identifiers, codes, types and parcel overlap shares. nwi_project_coverage_pct measures retrieved digital project footprint coverage, not the accuracy or completeness of real-world wetlands. nwi_imagery_years describes the mapped project imagery and can be old. Partial mapping is explicitly flagged.
Mapped area outside SFHA counts only the FEMA-mapped portion outside SFHA. It is NOT buildable acreage and does not subtract NWI wetlands, setbacks, access constraints, easements or other restrictions. Open parcel-screening.html locally to filter the CSV without uploading it.
Source documentation: https://www.fws.gov/program/national-wetlands-inventory/data-download
Limitations: https://www.fws.gov/page/national-wetlands-inventory-frequently-asked-questions

Evidence record_id refers to the original CSV parcel_id. No parcel identifiers or original values were replaced.


BOSTON FY2026 ASSESSMENT REVIEW (ATTRIBUTES ONLY)
Includes the complete official Boston FY2026 source CSV, retained byte-for-byte as assessment-current.csv, and assessment-source-provenance.json. The source dictionary remains available from its official URL in assessment-coverage.json. No new geometry is supplied by this CSV.

START HERE
1. Open owner-mail-review-queue.csv to review uniquely matched records with changed owner or mailing text. This is a verification queue, not a solicitation or confirmed transaction list.
2. Open assessment-review.csv for every original main-file record, side-by-side source values, source years, exact match status and assessment differences. Filter match_status for unresolved identifiers and outside_boston_scope.
3. Use assessment-current-unmatched.csv to investigate current Boston IDs with no unique original match. They are not necessarily new parcels.
4. Link parcel_id to the original parcels.csv for its dated mapped context. Do not apply old overlays to assumed new boundaries.

MATCHING AND CHANGE SEMANTICS
MassGIS TOWN_ID 35 + PROP_ID = Boston PID + MAP_PAR_ID = Boston GIS_ID. Both identifiers must match exactly, allowing only the documented trailing underscore on Boston identifier strings. Leading zeros are preserved.
Unique source keys only; both original and current matches checked for uniqueness. No address, name, fuzzy, spatial or padded-number matching. Incomplete identifiers, unmatched PIDs and map-key discrepancies remain unresolved. All original records remain in the review CSV. The separate source-location exceptions remain included unchanged.
Owner and mailing differences are text changes, including formatting changes, not confirmed sales, legal title, delivery validation or seller intent. Monetary comparisons ignore commas and decimal formatting; assessment differences are not market appreciation or tax bills. A zero original assessed total has no percentage difference. FY2026 is an assessment year, not current ownership verification.
Boston only (MassGIS TOWN_ID 35), not all Suffolk County municipalities. Other municipalities remain outside this comparison.

Preserved: original parcels.csv, parcels.geojson, flood/NWI evidence, samples, screening tool and the 16 original source-location exceptions. The original geometry and its overlays have not changed. FY2026 assessment records do not prove current ownership or permissions. Building/roof/heating/parking fields in the official source are dated assessor attributes, not inspection findings or current service needs.

Sector applications: brokers can review owner/mailing changes before refreshing research lists; appraisers can reconcile assessment years and values; contractors can inspect dated building attributes before site verification; public GIS teams can investigate unmatched keys. No source record alone establishes project feasibility or a qualified sales lead.

City of Boston, Assessing Department; Property Assessment FY2026, revision published May 22, 2026.
Source: https://data.boston.gov/dataset/e02c44d2-3c64-459c-8fe2-e1ce5f38a035/resource/ee73430d-96c0-423e-ad21-c4cfb54c8961/download/fy2026-property-assessment-data_rev.csv
Reuse: Open Data Commons Public Domain Dedication and License (PDDL) http://www.opendefinition.org/licenses/odc-pddl