Historic parcels

This topic applies to ArcGIS for Desktop Standard and ArcGIS for Desktop Advanced only.

In many cadastres, the chain of title is essential to the security of the present holder of the title. It is this evidence that validates a claim. A parcel database must not only provide an accurate representation of the current parcel boundaries but also an historic record of changes to the parcel boundaries. In the United States, the validity of title or rights on a parcel of land is based on evidence of previous land surveys and documents (a chain of evidence). Even in countries that guarantee title, the chain of records and boundary delineation is fundamental. New parcel surveys cannot be undertaken unless surveyors have access to previous survey information; survey data and past deeds or titles should never be discarded.

Historic parcels and plans

The parcel fabric tracks parcel history by both plan date (date on record of survey) and system date (date parcel changes were entered into the database). Two start date attributes (LegalStartDate and SystemStartDate) and two end date (LegalEndDate and SystemEndDate) attributes are stored on parcels and lines. The LegalStartDate attribute should correspond to the date of record of the current parcel's associated plan, and the LegalEndDate attribute should correspond to the date of record of the new, superseding parcels' associated plan.

When creating a new plan, if a LegalDate attribute is entered for the plan attributes, this attribute will be copied down to the LegalStartDate attribute of new parcels created in the plan. The LegalDate attribute is also copied down to the LegalEndDate attribute of any parcels that become historic as a result of a new parcel transaction, for example, merging parcels to create a new parcel.

When an existing parcel is replaced by parcels created in a new plan the existing parcel and its lines become historic. Parcel corner points don't necessarily become historic because adjacent parcels that share the point may still be current.

Historic parcels and parcel fabric adjustments

In the parcel fabric, historic parcels are important for both their legal role and their value in fabric adjustments. Historic parcels contain valid dimension data that provides increased measurement redundancy in a parcel fabric adjustment.

Continued adjustment of the parcel fabric means the point coordinates will change over time. Coordinates are the current best estimates of parcel corner locations. To track parcel lineage, the spatial relationship between current and historic parcels must be retained. Therefore, all parcel boundaries, both current and historic, will be part of any adjustment. Historic parcel boundaries will adjust with current parcel boundaries.

Historical attribute field

In the parcel fabric, the Historical attribute field on the Parcels table is set to 1 (true) for historic parcels. Active or current parcels have their Historical attribute field set to 0 (false).

The Historical attribute field is automatically set to 1 in the following cases:

• Parcel merge. Parcels being merged are flagged as historic.
• Parcel division. The parcel being divided is flagged as historic.
• Parcel Remainder. The original parcel is flagged as historic.
• New from parent. The parent parcel is flagged as historic.

The Historical attribute field on a parcel can be manually set to 1 (true) in the Parcel Details dialog box or by right-clicking a parcel and clicking Historic.

Historic parcels and database archiving

Since historic parcel boundaries participate in continued adjustments of the parcel fabric, history in the parcel fabric is dynamic. This contrasts with an archive of static information that is not edited or altered but retained. This is static history. Cadastres and the parcel fabric have both types of information. The recorded parcel dimensions on an historic parcel and any related title records are never altered and are considered static. Coordinates for these parcels change in a least-squares adjustment and are considered dynamic.

Displaying historic parcels in the parcel fabric layer

The History tab on the parcel fabric Layer Properties dialog box displays historic parcels in the parcel fabric layer. Under the History tab, you can choose to either display all parcels in the layer, or display parcels by legal or system date.

Displaying parcel history

To display parcel line history, you can either use definition queries on the lines layer to display parcel lines by date or Historic value or you can create a feature template for a historic line.

In the graphic below, both definition queries achieve the same goal, which is to display only current parcel lines. The first query displays only those lines that have no system end date and the second query displays only those lines with a History attribute field value of 0 (false). You can use other definition queries to display lines by legal date, date ranges, and so on.

Definition query to display current, non-historic parcel lines

Instead of hiding historic lines from the map display, you can define a historic line subtype and display parcel lines by their line type. For example, subdivision line, boundary line, historic line and so on.

In the Lines attribute table, if the Historic attribute field value is 1 (true) then you can set the subtype to a historic line.

Tip:

To display parcels that were current in a system or legal date range, specify a definition query on the parcels layer that queries the system and legal start/end dates.