By David J. Cowen

This image shows the boundaries of Town of Port Royal (yellow), South Carolina, in relationship to parcels (black lines) and census blocks (white lines). The figure demonstrates that the boundaries of incorporated areas often cannot be defined using census blocks. In this case, the boundary of Port Royal includes only a selected set of parcels that are separated by more than two miles of water and marsh. (Image generated by D. Cowen from Beaufort County, South Carolina, parcel data; Census Bureau data; and USGS orthoimagery.)

A land parcel is the representation of property that is often a family's most significant asset. Land parcel information is also the cornerstone of a host of public- and private-sector decision making. For those reasons, the National Research Council (NRC) conducted a study, National Land Parcel Data: A Vision for the Future, that examines the status of land parcel data in the United States and provides a set of recommendations that would foster a national system for land parcel data operated by the public sector. In many ways, this report is an update of the 1980 report The Need for a Multipurpose Cadastre. Clearly, much has happened since 1980. Institutionally, cadastre is considered a foundation layer for the Federal Geographic Data Committee's (FGDC) development of the National Spatial Data Infrastructure (NSDI). The FGDC Cadastral Subcommittee has developed a formal parcel data model and extensive documentation of the best practices and business plans. Technically, new data sources and sophisticated GIS data models have enabled thousands of local governments to capture and manage parcel data. Furthermore, several states now manage parcels as a function of state government. However, even though several federal agencies need parcel-level data to fulfill their missions, there is no federal government initiative to acquire and utilize parcel data.

Unfortunately, while the public sector is questioning whether it is technically and economically feasible to integrate parcel data, several private-sector firms are racing to complete just such a system. The most significant example is the recent acquisition by Nokia of NAVTEQ that places the value of accurate and current renditions of street centerlines and parcel-level street addresses at $8.1 billion. Furthermore, real estate-oriented firms have found parcel-level attribute data to be critical to their business applications. For example, Zillow currently maintains information about more than 70 million parcels that are accessed by two million visitors a month, and Blue Raster has developed an ArcWeb Services parcel Web service. It is also significant that Google utilizes Public Sector Mapping Agencies (PSMA) Australia data to support parcel-level geocoding across the country.

In order to address the needs for a public-sector approach to a national parcel data program, the committee developed a vision and series of findings and recommendations. The committee envisions a system that employs modern distributed database concepts and practices similar to those employed in many local governments or businesses. Each parcel would be a unique entity with feature-level metadata. In other words, parcels would be treated the same way FedEx tracks millions of packages. Ideally, this approach would not disrupt current systems, but it would enforce lines of stewardship and agreements to distribute data. This land parcel data system would include the following organizational characteristics:

• Built on already existing data systems, the system would link a series of servers maintained by local and state governments. The objective would be to seamlessly assemble accurate parcel information for any part of the nation at a given point in time.
• A national land parcel coordinator, working with coordinators for federal lands, Indian lands, and each state, would oversee the development and integration of consistent land parcel data.
• The data would be in the public domain; however, in order to protect privacy and confidentiality, no information would be provided about private ownership, use, or value.
• Each parcel would be a unique polygon (but not the legal document) with a minimum set of attributes that includes street address, unique identification number, a generalized category of ownership, and feature-level metadata that describes information about the data.

Addressing Specific Challenges

National Coordination—According to FGDC documentation, the Bureau of Land Management (BLM) is designated the federal steward for cadastre data, and it has carried out many important activities. A panel should be established to determine whether BLM has the necessary and sufficient authority and capacity to serve as the federal and/or national coordinator. If not, it should either be given the authority and resources or another agency should be named.

Incentives for Local Governments—Local governments fear that such a program would become another "unfunded mandate" and see few direct benefits. Therefore, it is important for the federal government to offer a series of carrots and sticks that would build meaningful and trusted partnerships with local and state governments. Where appropriate, federal agencies could require information based on parcel data to be eligible for federal funds. In return, the federal government should enter into cost-sharing arrangements to establish new parcel programs and fund programs, such as Imagery for the Nation, that would reduce local government costs.

Program Planning and Evaluation—The program would require a comprehensive business plan that would be managed by the national land parcel coordinator. This plan could follow developed benchmarks and metrics for assessing progress that have been developed by the FGDC Subcommittee for Cadastral Data.

Federally Managed Lands—The federal government should develop and maintain an inventory of its own property. A federal land parcel coordinator would coordinate the development and maintenance of a comprehensive and authoritative database for federally managed lands, including public lands.

Tribal Trust Lands—Parcel data in Indian lands is inconsistent across the nation. The Office of the Special Trustee for American Indians should establish an Indian lands parcel coordinator to coordinate the development and maintenance of a database for Indian trust parcels.

Census Bureau Address Data—It can be argued that the U.S. Census Bureau is spending several hundred million dollars to create its version of street centerlines and address points that are also being produced by companies such as NAVTEQ and Tele Atlas/TomTom. Congress and the U.S. Census Bureau should explore potential policy options, including modifications to Title 13 of the U.S. Code, which currently prohibits the bureau from sharing its address data. The committee believes that the substantial public investment in these files could be used to jump-start a program to complete parcel coverage for the two-thirds of the counties that do not currently have parcel data.

State-Level Coordination—Coordination at the state level is an essential part of the program and could logically be part of the Fifty States Initiative supported by the National States Geographic Information Council (NSGIC) and FGDC. This program should require that every state establish a state parcel coordinator, who would coordinate the linkage between all levels of government.

Funding—Many different sources of funding could support the program. Immediate and sustained funding for the program should be a shared responsibility among all stakeholders. Much of the funding should come from existing federal programs that require parcel data; however, new funding would be required to establish an initial baseline, integrate the data, and make it available. One of the great challenges is to find a way to take advantage of the private sector interest in parcel data.

Conclusion

The interest in a consistent set of parcel-level data is at an all-time high, and it is inevitable that such a system will soon exist. The question is whether private citizens will be able to access a system that is maintained by public officials who are accountable to voters and taxpayers.

About the Author

Dr. David J. Cowen is a professor of geography and codirector of the Center for GIS and Remote Sensing at the University of South Carolina, Columbia, South Carolina, and chair, NRC study, National Land Parcel Data: A Vision for the Future (e-mail: cowend@sc.edu).

More Information

Information about the report can be found at National Academy Press at books.nap.edu/ catalog.php?record_id=11978.