What Is a Parcel Map?

Picture a county from above, cut into pieces. Each piece is a parcel, a plot of land the county tracks as one unit for property records and taxes. A parcel map draws those pieces: an outline for each one and an ID number to go with it, so the assessor can tie every piece of ground to an owner and a tax bill. Esri's GIS dictionary defines it as “a geographic record of land ownership at the local level” used for surveying reference and tax assessment.

The parcel is the piece of land. Its boundary is the outline you see on the map. The APN is its ID number. The property information is whatever else is attached to that ID, such as address, acreage and owner.

Two Documents Share the Name

Search for “parcel map” and you'll see two different answers, because two different documents carry the name.

• The assessor's or GIS parcel map. The county's working map of every parcel, built for assessment and taxes. This is the map in county web viewers and in parcel apps, and it's what this guide covers. El Dorado County, California, notes that people often call its assessor's maps “parcel maps,” and that its staff sometimes have to ask which one a caller actually wants.
• The recorded parcel map. In California, a parcel map is a land division map under the state Subdivision Map Act. Kern County describes it as the map that creates four or fewer lots, with exceptions for some commercial, industrial and agricultural land. State law requires a registered civil engineer or licensed land surveyor to prepare it, and it ends up recorded with the county recorder.

What a Parcel Map Usually Shows

Which of these appear depends on the county and on the app, so treat this as a list of what to expect rather than a promise.

Parcel boundaries

The outline of each parcel. Neighboring parcels share edges, so you can see how the land is divided. The lines are approximate and drawn from records, not measured on the ground. Some assessor maps also print a bearing and distance along each line, copied from the recorded documents. Symbols differ from county to county; Placer County's key to its assessor maps uses a solid line for a property boundary and a dashed grey line for things like original lot lines, road boundaries and section lines.

Parcel identifiers

Most parcel maps show or let you look up the parcel's number. It may be called an APN, parcel ID or parcel number depending on where you are, and the format varies a lot. Whatcom County, Washington, builds its numbers from the township, range, section and map coordinates. Several California counties use the assessor's map book, page and parcel.

Numbers also change. El Dorado County's assessor says a parcel number is replaced when a parcel is split or combined, and that an old number is never reused. See What Is an APN? for the details.

Roads

Streets and roads are usually shown, and sometimes the road's right of way is drawn as a gap between parcels or outlined in a heavy line. Counties handle this differently, so don't assume the gap is the exact edge of the pavement.

Addresses

Many maps show a parcel's street address or let you search by it. An address and a parcel are not always one to one. See how to find property lines by address.

Acreage

An area figure, often in acres, taken either from the records or calculated from the outline. The two can differ slightly. Placer County adds a warning to its key: the acreage on its maps is “the amount of land you are taxed on, not necessarily the amount of land you own.” See How to Calculate Acreage of a Property to check a figure yourself.

Land ownership information

Some maps show the owner of record and mailing address from county records. This is where availability varies the most. Many counties publish it and some don't, and the data can lag behind recent sales. How to Find Out Who Owns a Property goes into this.

Why the Lines Are Approximate

Assessor maps exist to identify parcels for taxation. El Dorado County's guide says its assessor's map “does not have complete survey information,” and warns that paper copies may not be true to scale. The sample assessor map in Placer County's guide carries a note that it “was prepared for assessment purposes only” and that official information on the size of a parcel should come from recorded documents.

That's the whole reason a parcel map is good for finding land and weak for settling a boundary argument.

What a Parcel Map Does Not Show

• The legally determined boundary. Only a survey does that.
• Where the boundary markers are on the ground.
• Easements. El Dorado County's assessor states that its office does not keep track of or draw easements and sends people to the deed or a title search. A parcel with no easement drawn can still have one.
• Mineral or other split interests. In some California counties the mineral rights under a parcel carry their own APN, and the owner can be someone other than the surface owner.
• Zoning and setbacks, unless the map adds those layers separately.
• Anything about the property's title or condition.

What If One Property Has Two Numbers?

It happens, and the cause is usually administrative. A parcel crossing the line between two tax districts can receive two assessment numbers so each district gets its share of the bill. Or a single legal parcel is drawn in two pieces simply because it didn't fit on one map page. In the other direction, El Dorado County says it once let owners combine parcels under one APN to receive a single tax bill, and that this did not legally combine them. So one APN doesn't always mean one legal parcel, and one legal parcel doesn't always mean one APN. Practices differ by county. Ask the assessor, and check the recorded documents before relying on the count.

Where to Find a Parcel Map

• Your county's website. Many counties publish a GIS or parcel viewer. It's free, and as official as parcel data gets, but each county's tool looks and works differently.
• The county assessor. Often provides tax maps or links to the viewer.
• The county recorder or surveyor's office. The place to ask for a recorded map, such as a plat or a recorded parcel map.
• Mapping apps. These gather parcel data from many counties into one interface, which saves you from learning a new tool for each county.

Parcel Map vs Survey vs Plat

A parcel map is a general picture of how land is divided, mainly used for administration. A survey is a professional measurement of one property. A plat is a recorded drawing of a subdivision showing its lots and streets. Their roles overlap, and terms vary from place to place, but the key distinction holds: only a survey determines where a boundary is. See Property Line Map vs Land Survey.

Frequently Asked Questions

Is a parcel map a legal document?

The assessor's kind isn't a boundary document. It's prepared for assessment, and some counties say as much right on their maps. A recorded parcel map, as used in California, is a surveyed and certified document.

Who makes parcel maps?

For the assessor's kind, the county assessor's office or a GIS department. Parcel apps repackage county data. Recorded parcel maps are prepared by a licensed surveyor or engineer.

Is a parcel map the same as a plat map?

No. A plat is a surveyor's recorded drawing of a subdivision. In some counties the assessor's maps are also called plat maps, which adds to the confusion.

Can I get a parcel map of my property for free?

Often, through your county's online viewer. Printed or certified copies from a county office may cost a fee, which differs by county.

Common Mistakes

• Treating the outline as a surveyed line.
• Assuming every map shows ownership. Some don't, and others show outdated records.
• Assuming that the land you see inside a fence is the same as the parcel.
• Using a map from one county as if another county's numbers and symbols worked the same way.
• Measuring distances on a printout without checking whether it's to scale.

Now that you know what is on a parcel map, How to Read a Parcel Map shows you how to use one. If your goal is a boundary, start with How to Find Your Property Lines.

Sources

• GIS Dictionary: Parcel map (Esri) Definition of a parcel map.
• About Assessor’s Maps (El Dorado County Assessor, CA) Assessor’s maps vs recorded parcel maps, parcel number changes, easements.
• How to Read Your Assessor’s Parcel Map (Placer County, CA) Map key and assessment-only disclaimer.
• What is a parcel map (PM)? (Kern County Planning, CA) The recorded parcel map under the Subdivision Map Act.
• California Government Code, Parcel Maps, sections 66444–66450 Who prepares a recorded parcel map.
• Reading PDF Maps (Whatcom County, WA) How one county builds its parcel numbers.