Blog · October 14, 2026 · Pennsylvania
Reading the Carnegie Plat Map for a lot
A recorded plat shows how land near Pennsbury Village was divided into lots.
Main page: Allegheny County, PA GIS & Parcel Viewer (official map link, county facts and neighboring maps).
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When a listing near Rosslyn Farms mentions a lot number, look up the Carnegie plat map it refers to. What this Carnegie guide covers: where to request a copy, how a plat differs from a parcel map, and the details that matter to buyers.
Getting started with the Carnegie plat map
For a lot in Carnegie, the deed or parcel record often names the subdivision and plat reference; use it to request a copy.
The viewer Allegheny County publishes
Begin with the Allegheny County ArcGIS parcel map; it includes every assessed parcel around Pennsbury Village and Crafton. If the land is near Green Tree, type a street address, an owner's name or a parcel number, then pick the result to center the map on it. With a lot near Heidelberg, write down the parcel ID from that panel; each clerk in the county asks for it first.
When there's no plat
Rural land near Heidelberg that was never subdivided may have no plat at all; look for a recorded survey for land near Crafton.
On site with the map
The parcel map usually runs in a mobile browser, which helps when you're standing on land near Thornburg, but coverage can be spotty out of town. A screenshot of the parcel near Rosslyn Farms with its ID helps when you meet an owner or agent.
Land on the county line
For a home near Heidelberg, allegheny County meets Armstrong County, Beaver County, Butler County, Washington County, and Westmoreland County, all with their own assessor records. A tract near the line by Green Tree can be split in two county records, so look at the neighboring map before you assume the acreage. If you're looking near Green Tree, our state page lists each neighboring county map across Pennsylvania.
Deeds, plats and who keeps them
The map is an index, not the title: recorded deeds, plats and easements covering ground around Thornburg sit with the Recorder of Deeds. Older tracts near Pennsbury Village may go back through several deeds, so a title company earns its fee before a purchase.
Where Carnegie fits in
Carnegie is part of Allegheny County, Pennsylvania, and the county assessor maps its lots. If you're looking near Pennsbury Village, city or town hall handles matters such as zoning, permits and utilities within town limits, and the county still keeps the parcel and deed records. Acreage past the city limits out by Rosslyn Farms generally falls under county rules instead.
Who handles what
If the acreage or value on a parcel near Rosslyn Farms looks off belong with the county assessment office, which maintains the tax roll. Questions about what you can build around Rosslyn Farms are for the local planning and health departments, town or county, depending on location.
Plat map vs. parcel map
When the two disagree for a lot near Pennsbury Village, the recorded plat and a survey control.
Replats and vacations
An amended plat may change lots around Thornburg, so check for later filings; street vacations near Pennsbury Village show up in the records too.
Reading the plat sheet
Utility or drainage strips on a lot in Carnegie can block a shed or pool; check the plat notes and any covenants.
Ordering the Carnegie plat map
On ground around Rosslyn Farms, some counties put plat images online, while others require a visit or a request; copy fees are usually small.
Sections, lots and bearings
Older tracts around Crafton commonly use metes-and-bounds descriptions, a series of courses and distances from a starting point. Subdivision lots in Rosslyn Farms usually use lot and block from a recorded plat instead, making them easier to find. Keep the legal description for land near Green Tree for any title or survey request.
Allegheny County in a few facts
With a lot near Pennsbury Village, pittsburgh is the county seat, where most land records are kept. Smaller places on the map include Rosslyn Farms, Heidelberg, Pennsbury Village, and Green Tree, where town lots give way to larger tracts. On ground around Thornburg, about 1,224,825 people call Allegheny County home (Census estimate, 2023) across some 730 square miles. For a tract near Pennsbury Village, allegheny County dates to 1788, which matters when you trace an old farm's title. Features like Allegheny River and Monongahela River help you orient on the aerial around Crafton.
What the map can't tell you
Listed acreage is an assessed number; just a licensed surveyor establishes the real lines on land around Pennsbury Village. Closer to Green Tree, records update in batches, so a deed recorded last month can take weeks to appear.
Frequently asked
Are old plats online near Thornburg?
For a home near Pennsbury Village, it varies; some offices have scanned older plats and some haven't; call before you visit.
How do I get a copy of a plat in Carnegie?
Generally, recorded plats near Rosslyn Farms are filed with the Recorder of Deeds.
How is a plat different from the parcel map near Pennsbury Village?
If you're looking near Heidelberg, a recorded plat is based on a survey, but the GIS map is not.
What do the dashed lines on a plat mean in Carnegie?
Building on an easement near Heidelberg is generally restricted; ask planning staff if unsure.
How is land described in Pennsylvania deeds for land near Pennsbury Village?
With a lot near Thornburg, Deeds use lot and block, metes and bounds or survey descriptions; copy it for any survey or title request.
Open the official Allegheny County, PA parcel map See it in the Platbookmapper directory
Not a survey. County GIS and tax parcel maps are assessment and planning layers. They are not a substitute for a recorded plat, deed, or licensed survey, especially for fences, setbacks, or boundary disputes.