data, there was little integration among the components of this entity. The cost and time associated with the compilation, drafting, printing, and distribution of paper maps prohibited such integration.
The introduction of the digital computer in the 1960s and 1970s led to two major developments in mapping. First, the printed map can be produced by using the new, more flexible digital technology. Second, the printed map is increasingly being supplemented and replaced by computer-based geographic information systems (GIS), which treat maps as a series of spatially integrated layers. While paper maps originated to supplement human memory and vision, GIS do this and more: they supplement human cognitive or information-processing capabilities as well.
In the GIS era it is no longer adequate to speak of a "cartographic enterprise" with its connotation of simply making paper maps. Instead we must develop new conceptions more useful in describing and analyzing how geographic data (any data referenced to location) are acquired, processed, disseminated, and used.
Unlike maps, strings of geographic or spatially referenced digital data can be aggregated, transformed, and shared. Spatial data can now be more easily isolated and abstracted from the particular application in which it was developed and channelled into other settings and other GIS where it can be reused, enhanced, and routed to other potential user communities. The old "top down" model (especially appropriate for base data from NMD and other federal agencies) is inadequate to represent the multidirectional alternative information flows that are now technically feasible.
Spatially referenced digital data can perhaps be thought of as molecules of water that in aggregate form a circulating fluid, flowing freely from application to application (or from system to system). Conceived of in this fashion, information can be seen to take on value and become a marketable commodity, quite apart from the context, need, or application for which it was originally developed.
An important qualification to this concept must, however, be clearly stated. It is often said that our nation's economy is becoming information-based, and statistics are produced to show its considerable economic value. It is critical to recall (as many journalists do not) that while information seems to have a reality of its own, it takes on value only with reference to authentic value-producing activity, that is, only when it is about something. For example, even though a timber products firm might like to buy rather than produce basic mapping of its resources and facilities