Geographic information systems (GIS) are computer-based information systems that work with geographic or spatial data. The term GIS is also used to describe the whole discipline dealing with geographic information systems or geographic information science. A GIS can produce maps, but its unique attribute is the ability to integrate and analyze spatial data and related statistical or descriptive data. GIS has been described as "perhaps … the most significant event in spatial data handling since the invention of the map" (Pickles 1995, p. 49). Like maps and any information production system, from writing to scientific research, GIS involves basic ethical questions of truthfulness, equity, and power. Maps are graphical depictions of the nature and spatial relationships of objects—they are generalized, simplified representations of reality. Cartographers strive to produce value-free, objective maps, but maps are also cultural and rhetorical texts imbued with social significance (Harley 2001). The symbols...