and consists of information concerning the built and human environment versus one dominated by natural resources. The expenditures for acquiring and encoding information defining and pertaining to places are made in an ad hoc manner and redundantly by federal agencies, local governments, and the private sector. Thus, what could be a national investment frequently goes no further than an expense.
We divided this fabric into the following four pieces:
the land base and use of land,
the ownership of the land,
the transportation (street) network that serves it, and
the addressing schemes that provide common geographic reference.
We discuss these pieces in the above context.
The point of departure for this discussion is the findings and recommendations in the report—Spatial Data Needs: The Future of the National Mapping Program (MSC, 1990)—that digital, spatial data bases be developed to serve both public and private needs of the country. We studied the case of the urban fabric to consider the needs of urban areas for digital spatial data, to determine how well currently available systems for supplying and maintaining spatial data meet these needs, and to determine how the availability and accessibility of urban spatial data in the future might be improved.
An urban spatial data base is a digital system that defines location and/or spatial references (addresses) of objects, people, and events. The committee identified four general kinds of urban spatial data. This chapter addresses the potential contribution of each toward meeting the needs for an adequate spatial data infrastructure for urban areas of the United States and the current status of each one. In Chapter 9 we present recommendations for technical, organizational, and institutional changes and for cooperative activities to meet the needs for urban spatial data in the next decade. The four components of an urban spatial data base are (1) the urban land base system (planimetric and topographic); (2) the cadastral system; (3) the street centerline system; and (4) the political and administrative boundary system (not further discussed).