the technical capability, some significant obstacles stand in the way of creating consistent, accurate, and timely digitized parcel data on a national basis.

5.1.1
Dynamic Nature of Land Records

Ideally parcel data reflect the current status of ownership, use, and value of a piece of real estate. Since there are numerous transactions that change any of these factors as well as the actual boundaries, there is often a time lag between the recorded or actual legal transaction and what is reflected in the published digital layer. Parcel maps are constantly changing with new subdivisions, annexations, corrections, and other routine modifications. Figure 5.1 shows how the parcel data for Kern County, California, changed from 2005 to 2006.

Keeping up with the large number of transactions that may occur in any jurisdiction’s parcel database is time consuming and must be handled at the local level because current parcel information is needed for many aspects of local government. The current ownership status is used in permitting, emergency response, land use planning, real estate taxation, and many other local government functions. The number of people and the resources required to keep a parcel data set current vary with the number of new transactions, whether maps and documents are submitted digitally, and the level of automation of the transactions affecting new parcel creation. Sifting through all recorded documents in hard-copy form to find those that affect parcel geometry changes is a daunting task.

How these transactions are implemented varies greatly among local government. In some cases the deed and recorded transaction is updated almost instantaneously, and the real estate record and then the mapping follows. In other jurisdictions, all of the changes are made at once. Any combination of update cycles can be found across the country. Inconsistent maintenance cycles mean that, in many cases, the digital map may not have the most up-to-date attributes available or the mapping may not reflect the current transactions for splits, combination, or new parcels. Furthermore, many jurisdictions outsource this work and obtain a new digital parcel layer in-house only once a year to

FIGURE 5.1 Example of parcel data in Kern County, California, in 2005 and 2006. SOURCE: Map created by First American Flood Data Services. Data provided by Kern County, California.



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement