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FAQs

What is a GPIN?

The Grid Parcel Identification Number (GPIN) is a unique 10-digit number that represents an x, y coordinate on the Prince William County proprietary grid. GPINs are calculated using GIS software. Each time the boundary of a parcel changes, a new GPIN is calculated, reflecting the new center of the parcel. The parcel's history can then be tracked using it's "parent" GPIN.

Because the GPIN is a coordinate identifier rather than a hierarchical identifier, the number is not related to size or any other characteristics of the polygons and gives no information about what subdivision a parcel belongs to or what parcel it was created from. That information is derived from related tables describing the subdivision and the parent-parcel.

Any parcel separated by a road and/or having noncontiguous polygons for any reason is still considered a single parcel and is assigned one GPIN. However, each polygon associated with that parcel will be assigned an individual centroid.

GPINs can be used to quickly locate the parcel on a County map or within County applications. GPINs link data between many County agencies, therefore, in order for the County to provide information to customers in a seamless environment, a GPIN is required before issuing permits.

Creating new parcels begins with the review of proposed development plans. Addresses are assigned to each proposed parcel during the review process. Once the approved plan/plat is recorded at the courthouse, a copy is forwarded to our office and the Geographic Information System (GIS) is updated with the parcel information and the new GPIN is created. This process may take several weeks to complete after which the information is available in the County's GIS database.

How is a GPIN assigned?

The GPIN is based on a combination of Easting (X) and Northing (Y) values at the center of a parcel, based on the Prince William County proprietary grid. It is a unique identifier that references location only, and carries no other parcel attribute information. The GPIN can be thought of as having a telescopic or 'zooming' effect on defining the parcel location in an area, by identifying a 10,000' square, then a 1,000' square, and finally a 10' square, all within the original 10,000' square. This reduces the time required for a user to search a crowded mapsheet for a small parcel.

The 4 digit XXYY coordinate references a 10,000' grid square. This coordinate is defined by a combination of the 100,000’ and 10,000’ place digits of the Easting(x) and Northing(y) values. The millions places are not a part of the GPIN identifier since all the parcels in Prince William County can be identified uniquely without reference to them. 

Example 1.1:

X: 11720450 – 72

Y:   6981170 – 98

This coordinate value would produce 7298 as the initial 4 position portion of a GPIN (7298-XY-XXYY).

The next set of coordinates is XY, referring to the 1,000 place digits in the Easting(x) and Northing(y) values. This coordinate further narrows down the location of the parcel by defining the 1,000' square in which the parcel lies.

Example 1.2:

X: 11720450 – 0

Y:   6981170 – 1

This coordinate value would produce 01 as the initial 2 position portion of a GPIN (7298-01-XXYY),

The next set of 4 digits narrows down the parcel centroid location to a 10' square.  It is composed of the 100’ and 10’ place digits in the Easting(x) and Northing(y) values.

Example 1.3:    

X: 11720450

Y: 6981170

This coordinate value would produce 4517 as the final 4 position portion of a GPIN (7298-01-4517). 

The last set of two digits (ZZ) is used only for parcels where there is an above ground interest as in the case of condominiums. The Z value (01-99) indicates the level of the condominium unit within the building. A value of 01 is used for the very bottom level of a building.

Mapsheets at scales of 1"=200' and 1” = 300’ are identified using the 4 digit 10k number an alpha quad identifier of NE, SE, NW or SW to identify the quarter of the 10k Area of Interest.

How do I find the GPIN for a parcel?

Customers can find the GPIN for a parcel by accessing one of our interactive mappers such as QuickInfo or County Mapper and entering in the parcel's address.

Where can I get aerial photographs of Prince William County?

The 1937, 2004, 2006, 2008, 2009, 2011, 2013, 2015, 2017, 2019, 2021, and 2023 aerial photography are available using the online County Mapper application. 

Prince William County GTS no longer sells digital orthography tiles. Imagery may be obtained at no cost through the Virginia Geospatial Information Network (VGIN) as true color and infrared services made available for use. Countywide aerial imagery may be accessed here. 

Can I find the owner of property in Prince William County?

Property ownership information is provided by the Real Estate Assessments office. You may contact them directly at 703-792-6780 if you already know the property address, or you can visit their Real Estate Property Assessment Information website. To obtain the property address, please contact the GIS Office and provide one of the following pieces of information:

  • The Legal Description
  • The Grid Parcel Identification Number (GPIN)
  • The old tax map number (if applicable)

What is Geographic Information System (GIS)?

A Geographic Information System (GIS) allows the user to capture, store, integrate, manipulate, analyze and display spatial and tabular information about the world as a collection of thematic layers that can be linked together by geography. Patterns, relationship and trends can be visualized that cannot otherwise be seen in a table or list format. This simple but extremely powerful and versatile concept has proven to be invaluable for solving many problems from developing school bus routes, to recording details of land development, to modeling future transportation needs.

How are addresses created?

New addresses are assigned to new parcels as development occurs. Addresses can be changed when problems, such as the following, arise:

  • Streets are renamed
  • Address numbers are duplicated
  • Address numbers are out of sequence
  • Driveway locations are on corner lots

When addresses are changed, notification is mailed to all property owners involved or affected by the change. Notification is also sent to County agencies, utility companies, and post offices.

For more information on addressing, go to the addressing main page or contact our office at 703-792-6840.

What are Service Authority Address Listings?

Address listings for new developments must accompany any requests for a Utility Permit. Utility Permit fees and Tap fees cannot be paid until this form is received by Engineering at Prince William County Service Authority.

Addresses are assigned during the review of proposed development plans. This information is then provided to the developer. The developer must type the addresses onto the Service Authority Address Listing form once the plan is approved.

The completed address listing may be sent to the GTS Office for verification via hand delivery, fax, or mail. The address verification process requires one business day, after which, the listing, with the original approval signature, is available for pickup at the GTS Customer Service counter. The Service Authority requires the original signature on the approval sheet and will not accept facsimiles.

What is the difference between a parcel address and a premise address?

Parcel addresses are assigned to a single piece of land. Premise addresses are assigned to buildings and/or units that are located on a parcel of land. In cases where the parcel of land contains a single structure that is owner-occupied, the parcel address and premise address are the same. In cases where many structures are located on the same parcel (such as apartment complexes or business parks), the premise address will be different than the parcel address.

Where can I find your available map products?

Map products are available free of charge on the Prince William County GIS Data Portal. There you can download maps of your choice and take the electronic file to a local print shop for printing services. Recommended print sizes are listed under the map title.

You can also find many spatial data layers on County Mapper, and print directly from that site. 

How do I obtain a copy of my subdivision plat?

The Clerk of the Court has all recorded subdivision plats and deeds on file. A subdivision plat shows every lot in a subdivision; it does not show buildings or their dimensions. Copies of subdivision plats are available for purchase at the Circuit Court Clerk's Office. 

How do I find a copy of my home's survey plat?

A house location survey shows the boundaries of the parcel as well as the location of the house. It will show the distance from property edges to the house and the dimensions of the house footprint. Neither the Prince William County offices nor the Courthouse keep copies of the individual house location survey plats. If you need a house location survey, try one of the following resources:

  • Your lender or mortgage company
  • The surveyor that was used for the settlement
  • Your settlement papers
  • The settlement attorney
  • The title company that handles the sales transaction