A system for the Input, retrieval, display, and overlay of 2-dimensional geographical data sets has been developed. The Geographical Information and Display System (GIDS) has been designed according to the following criteria: the system should be easy to use, easy to evolve, problem-independent, interactive, and graphic-oriented. Thematic map data are encoded by locational data elements (points, lines, or polygons) over which some attribute is homogeneous. Both the attribute and locational data are then input to GIDS and stored in sequential file structures, from which they can be selectively retrieved, displayed, and manipulated at user request. All user requests to the system may be expressed interactively via an English-like command language. Each command, corresponding to one operation such as input, display or overlay, is interpreted and executed by an independent module which accesses the data through a common input/output framework. GIDS has proved useful to planners and researchers because of Its ability to display and relate data from different maps. / Science, Faculty of / Computer Science, Department of / Graduate