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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 /api/parcel-record. 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.

Plant details: /api/power/plants/{plant_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 a point: /api/utilities/context

Data-center projects

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

Within 10 km of a point: /api/datacenters/context

Grid capacity data

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

Sources and dates: /api/grid/capacity/summary

Flood zones and wetlands

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

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 of a point: /api/logistics/context

Example requests for Middlesex County

Real responses from the production API, trimmed to the main fields. Every request needs an API key with api:read; see authentication and credits and limits.

1. Find a parcel by address

/api/search matches 50 INNER BELT RD, SOMERVILLE, MA and returns the parcel's korzy_id, coordinates and record. 1 credit.

curl --fail-with-body -sS --get \
  -H "Authorization: Bearer $KORZY_API_KEY" \
  --data-urlencode 'q=50 INNER BELT RD, SOMERVILLE, MA' \
  https://api.korzy.co/api/search
Python
import os
import requests

response = requests.get(
    "https://api.korzy.co/api/search",
    params={"q": "50 INNER BELT RD, SOMERVILLE, MA"},
    headers={"Authorization": f"Bearer {os.environ['KORZY_API_KEY']}"},
    timeout=30,
)
response.raise_for_status()
parcel = response.json()["results"][0]
print(parcel["korzy_id"], parcel["longitude"], parcel["latitude"])
Response (trimmed)
{
  "results": [
    {
      "korzy_id": "25017-6187a01e29a295aa8ab0",
      "address": "50 INNER BELT RD",
      "city": "SOMERVILLE",
      "postcode": "02143",
      "county": "Middlesex",
      "statefp": "25",
      "longitude": -71.08033194059567,
      "latitude": 42.37802645,
      "match_type": "exact",
      "parcelid": "110 B 1",
      "parceladdr": "50 INNER BELT RD",
      "parcelcity": "SOMERVILLE",
      "situs_zip": "02143",
      "yearbuilt": 2009,
      "bldgsqft": 45621,
      "taxacres": 2.2957,
      "totalvalue": 19116900,
      "saledate": "2011-01-05",
      "saleamt": 100,
      "updated": "2026-11-03",
      "geoid": "25017"
    }
  ],
  "truncated": false
}

2. Look up the parcel at a point

/api/query/point returns every parcel whose boundary covers the coordinates; here it returns the same record, 25017-6187a01e29a295aa8ab0, in records. 1 credit per 10 records requested.

curl --fail-with-body -sS --get \
  -H "Authorization: Bearer $KORZY_API_KEY" \
  --data-urlencode 'longitude=-71.080332' \
  --data-urlencode 'latitude=42.378026' \
  --data-urlencode 'limit=5' \
  https://api.korzy.co/api/query/point
JavaScript
const params = new URLSearchParams({"longitude": "-71.080332", "latitude": "42.378026", "limit": "5"});
const response = await fetch(`https://api.korzy.co/api/query/point?${params}`, {
  headers: { Authorization: `Bearer ${process.env.KORZY_API_KEY}` },
});
if (!response.ok) throw new Error(`Korzy API ${response.status}`);
const { records } = await response.json();
console.log(records.map((record) => record.korzy_id));

3. Check nearby data-center projects

/api/datacenters/context lists data-center projects within 10 km of the point, nearest first. 1 credit per 10 records requested.

curl --fail-with-body -sS --get \
  -H "Authorization: Bearer $KORZY_API_KEY" \
  --data-urlencode 'longitude=-71.080332' \
  --data-urlencode 'latitude=42.378026' \
  --data-urlencode 'radius_km=10' \
  --data-urlencode 'limit=3' \
  https://api.korzy.co/api/datacenters/context
Python
import os
import requests

response = requests.get(
    "https://api.korzy.co/api/datacenters/context",
    params={"longitude": "-71.080332", "latitude": "42.378026", "radius_km": "10", "limit": "3"},
    headers={"Authorization": f"Bearer {os.environ['KORZY_API_KEY']}"},
    timeout=30,
)
response.raise_for_status()
for project in response.json()["projects"]:
    print(project["name"], project["status"], project["distance_km"])
Response (trimmed)
{
  "projects": [
    {
      "project_id": "dc_affc631d1443badb7741",
      "name": "Evocative BOS1 (Somerville)",
      "operator": "Evocative",
      "status": "operating",
      "city": "Somerville",
      "state": "MA",
      "longitude": -71.080419,
      "latitude": 42.377932,
      "location_precision": "approximate",
      "operational_mw": 6,
      "distance_km": 0.012661793105670349
    },
    {
      "project_id": "dc_f6aded03714cf69cbe8c",
      "name": "CoreSite BO1 - Boston, MA",
      "operator": "CoreSite",
      "status": "operating",
      "city": "Somerville",
      "state": "MA",
      "longitude": -71.07975762422522,
      "latitude": 42.37670585,
      "location_precision": "footprint",
      "distance_km": 0.15418992243174356
    },
    {
      "project_id": "dc_ab9a9453cda30829b7ca",
      "name": "DataBank BOS1 - Downtown Boston",
      "operator": "DataBank",
      "status": "operating",
      "city": "Boston",
      "state": "MA",
      "longitude": -71.060271,
      "latitude": 42.354699,
      "location_precision": "approximate",
      "operational_mw": 0.5,
      "distance_km": 3.073177992359499
    }
  ],
  "radius_km": 10,
  "limit": 3,
  "truncated": true
}

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. /api/datacenters/context lists projects within 10 km of any 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%. /api/utilities/context returns the water and sewer matches at a point.

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Build on Middlesex County parcel data

Search, point and record lookups work the same in every county Korzy covers. Credits are shared across parcels, utilities, environment, logistics and data-center routes.

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