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Middlesex County, MA parcel and infrastructure data API

Korzy has about 530,000 parcel records for Middlesex County, Massachusetts, with source updates through November 2026. Nearly every record carries values and last sale; 94% include building size and 91% include year built. In and around the county the API also maps 8 data-center projects (8 operating); about 60 power plants with about 520 MW of capacity, led by natural gas; and 1 port with reported cargo. Look up any parcel by address or coordinates, then check nearby data-center projects, utilities and grid context at the same point.

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Parcel coverage in Middlesex County

About 530,000 parcel records with boundaries, situs addresses and parcel numbers, with the latest source update from November 2026. Each record has a stable korzy_id you can store and look up again with /v1/records/{id}. Share of records with each field:

FieldCoverageShare
Situs addressNearly all · 99%
Owner nameNot published
Assessed or market valueNearly all · 99%
Year builtMost · 91%
Building sizeMost · 94%
Last saleNearly all · 99%
Land useNot published
ZoningNot published

Middlesex County records do not include owner names. See pricing for credit costs.

Infrastructure in and around Middlesex County

Power plants

About 60 operable plants with about 520 MW of nameplate capacity; largest by capacity: natural gas, solar, oil. Proposed generators add 5 MW.

Within 50 km: /v1/lookup section power; details: /v1/records/{id}

Substations and transmission

About 100 in-service substations, about 10 rated 230 kV or higher.

About 480 miles of transmission lines: about 40 mi at under 100 kV; about 270 mi at 100–161 kV; about 40 mi at 220–287 kV; about 110 mi at 345 kV; about 10 mi at DC.

Water and sewer service

Service areas of about 120 community water systems cover about 61% of the county.

Sewer service areas of about 15 systems cover about 37%.

At an address or point: /v1/lookup section utilities

Data-center projects

8 tracked projects: 8 operating. Reported planned capacity: about 50 MW.

Within 10 km: /v1/lookup section datacenters

Grid capacity data

2 utility-published grid capacity layers cover parts of Middlesex County, including loading forecasts, substation inventory.

Nearby records: /v1/lookup section grid

Flood zones and wetlands

Special flood hazard areas cover about 13% of the county on the current federal flood maps, published October 2026.

Mapped wetlands cover about 10%.

At an address or point: /v1/lookup section environment

Rail, ports and freight

  • About 180 miles of active rail, about 150 of it main line
  • About 100 miles of national freight network highway
  • 1 port area with reported cargo tonnage

Within 25 km: /v1/lookup section logistics

Example requests for Middlesex County

The lookup response is a real production response, trimmed to the main fields. Every request needs an API key with api:read; see authentication and credits and limits.

1. Find a parcel and nearby data-center projects

/v1/lookup matches 50 INNER BELT RD, SOMERVILLE, MA and returns the parcel's korzy_id and record, plus the data-center projects within 10 km, nearest first. 2 credits.

curl --fail-with-body -sS \
  -H "Authorization: Bearer $KORZY_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"address":"50 INNER BELT RD, SOMERVILLE, MA","sections":["datacenters"]}' \
  https://api.korzy.co/v1/lookup
Python
import os
import requests

response = requests.post(
    "https://api.korzy.co/v1/lookup",
    json={"address": "50 INNER BELT RD, SOMERVILLE, MA", "sections": ["datacenters"]},
    headers={"Authorization": f"Bearer {os.environ['KORZY_API_KEY']}"},
    timeout=60,
)
response.raise_for_status()
body = response.json()
parcel = body["parcels"]["records"][0]
print(parcel["korzy_id"], body["sections"]["datacenters"]["status"])
Production response (trimmed)
{
  "location": {
    "longitude": -71.08033194059567,
    "latitude": 42.37802645,
    "address": "50 INNER BELT RD, SOMERVILLE",
    "match_type": "exact"
  },
  "parcels": {
    "records": [
      {
        "id": "25017-6187a01e29a295aa8ab0",
        "korzy_id": "25017-6187a01e29a295aa8ab0",
        "parcelid": "110 B 1",
        "parceladdr": "50 INNER BELT RD",
        "parcelcity": "SOMERVILLE",
        "situs_zip": "02143",
        "statefp": "25",
        "geoid": "25017",
        "longitude": -71.08033194059567,
        "latitude": 42.37802645,
        "yearbuilt": 2009,
        "bldgsqft": 45621,
        "taxacres": 2.2957,
        "totalvalue": 19116900,
        "saledate": "2011-01-05",
        "saleamt": 100,
        "updated": "2026-11-03"
      }
    ],
    "truncated": false
  },
  "sections": {
    "datacenters": {
      "status": "ok",
      "data": {
        "radius_km": 10,
        "projects": [
          {
            "id": "datacenter:dc_affc631d1443badb7741",
            "project_id": "dc_affc631d1443badb7741",
            "name": "Evocative BOS1 (Somerville)",
            "operator": "Evocative",
            "status": "operating",
            "state": "MA",
            "city": "Somerville",
            "address": "50 Inner Belt Road",
            "longitude": -71.080419,
            "latitude": 42.377932,
            "location_precision": "approximate",
            "operational_mw": 6,
            "source_count": 1,
            "source_date": "2026-09-15",
            "mapped": true,
            "distance_km": 0.012705876479046566
          },
          {
            "id": "datacenter:dc_f6aded03714cf69cbe8c",
            "project_id": "dc_f6aded03714cf69cbe8c",
            "name": "CoreSite BO1 - Boston, MA",
            "operator": "CoreSite",
            "status": "operating",
            "state": "MA",
            "city": "Somerville",
            "address": "70 Innerbelt Rd",
            "longitude": -71.07975762422522,
            "latitude": 42.37670585,
            "location_precision": "footprint",
            "source_count": 3,
            "source_date": "2026-09-15",
            "mapped": true,
            "distance_km": 0.15423606828196126
          },
          {
            "id": "datacenter:dc_ab9a9453cda30829b7ca",
            "project_id": "dc_ab9a9453cda30829b7ca",
            "name": "DataBank BOS1 - Downtown Boston",
            "operator": "DataBank",
            "status": "operating",
            "state": "MA",
            "city": "Boston",
            "address": "1 Summer Street Suite 704",
            "longitude": -71.060271,
            "latitude": 42.354699,
            "location_precision": "approximate",
            "operational_mw": 0.5,
            "source_count": 1,
            "source_date": "2026-09-21",
            "mapped": true,
            "distance_km": 3.0732176052443543
          }
        ],
        "truncated": false,
        "note": "Straight-line distance to the reported project point; inspect location_precision. Projects merge supported source matches, not every nearby building. Approximate locations do not identify a parcel. Reported IT load, facility power, planned capacity and estimates remain separate source claims. No record or unknown status does not establish absence or inactivity."
      },
      "provenance": [
        {
          "dataset": "datacenters",
          "as_of": "2026-11-02",
          "data_version": "20261102T123021962884Z"
        }
      ]
    }
  },
  "credits": {
    "charged": 2,
    "refunded": 0
  }
}

2. Add value and sale fields

/v1/enrich returns the fields you choose for up to 25 parcels per request; here the parcel 25017-6187a01e29a295aa8ab0. 1 credit.

curl --fail-with-body -sS \
  -H "Authorization: Bearer $KORZY_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"items":[{"korzy_id":"25017-6187a01e29a295aa8ab0"}],"fields":["identity","value","sale"]}' \
  https://api.korzy.co/v1/enrich

3. Fetch the record again by ID

/v1/records/{id} returns the stored parcel's full record, without owner fields. 1 credit.

curl --fail-with-body -sS \
  -H "Authorization: Bearer $KORZY_API_KEY" \
  https://api.korzy.co/v1/records/25017-6187a01e29a295aa8ab0
JavaScript
const response = await fetch(`https://api.korzy.co/v1/records/${encodeURIComponent("25017-6187a01e29a295aa8ab0")}`, {
  headers: { Authorization: `Bearer ${process.env.KORZY_API_KEY}` },
});
if (!response.ok) throw new Error(`Korzy API ${response.status}`);
const { record } = await response.json();
console.log(record.parceladdr, record.usedesc);

Middlesex County data questions

How many parcels in Middlesex County include year built?
About 480,000 of about 530,000 parcel records (91%) include year built.
Does the Korzy API return owner names for Middlesex County parcels?
Middlesex County parcel records do not include owner names. Values, land use and building facts are returned where the county publishes them.
How many data-center projects are in Middlesex County?
Korzy tracks 8 data-center projects in Middlesex County: 8 operating. A /v1/lookup with the datacenters section lists projects within 10 km of any address or point.
How much power generation is in Middlesex County?
About 60 operable power plants in Middlesex County total about 520 MW of nameplate capacity, mainly natural gas, solar and oil.
Which water systems serve Middlesex County?
Service areas of about 120 community water systems cover about 61% of Middlesex County, and sewer service areas cover about 37%. A /v1/lookup with the utilities section returns the water and sewer matches at an address or point.

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Build on Middlesex County parcel data

Lookups, enrichment and records work the same in every county Korzy covers. Credits are shared across parcels, utilities, environment, logistics, power, grid, data-center and terrain sections.

Get an API keySee pricingAPI referenceUse cases for parcel and infrastructure data