Using GIS to Document, Visualize, and Interpret Tokyo's Spatial History

Social science historians bring a wide range of topical interests and methodological skills to the investigation of historical conditions. Those with an interest in the changing distribution and locational relationships of social, demographic, economic, political, cultural, physical, and other phenomena may now be considering the use of geographic information systems (GIS) for historical analysis. As an urban form historian and mapping scientist who uses GIS to document, visualize, and interpret spatial history, I am writing this account of my development of a GIS spatial history of Tokyo with the hope that it will convey the benefits and challenges of using GIS for historical research.

Why use GIS for historical research? There is a simple, two-part answer. First, humans are spatial beings. Individuals, groups, and institutions exist and interact in natural and human environments that occupy space over time. Human history necessarily includes a spatial dimension, which historians often overlook. Second, geographic information systems are designed to record spatial features and related information, display them, and analyze their conditions and spatial relationships. These capacities enable spatial historical research and extend its analytical reach.

Historical spatial information is often hard to deal with. It is found in a diverse range of sources, such as maps (with various scales, cartographic styles, levels of detail, degrees of accuracy), urban plans, photographs (aerial and ground-level), and census, economic, institutional, and voting records. Comparing spatial information from one of these sources with information from another, or with information from the same type of source but a different time period, can be complicated and difficult, especially for historians who are not familiar with spatial sources or the specialized cartographic techniques that enable one to glean the most from visual spatial information. Patterns in social statistical data, however, are often hard to grasp unless the data can be explicitly mapped to the corresponding spatial areas. By linking historical spatial information to corresponding geographic features in a computerized cartographic database, geographic information systems make it possible to record, display, and evaluate relationships between types of information that were in hard-to-compare formats or spread over many sequential historical maps.

Many aspects of the history of an urban region’s form can be recorded to produce an integrated spatial database. For example, the GIS can include changes in visible spatial features such as land cover, transportation networks, and physical geography. Changes in abstract spatial features such as political units and boundaries, socioeconomic patterns, and demographic data from censuses and other sources can also be incorporated. Temporal events or other information can often be linked to spatial features, such as linking corporate events and business performance statistics to the geographic locations of different branches and customers, or linking organizational events in the history of a railroad company to the rail lines, stations, and service areas affected by mergers and acquisitions.

Integration of this diverse information allows analysis of relationships that might not otherwise have been considered. For example, a GIS can be used to display at a similar scale the urban patterns seen in various historical maps and aerial photographs and recorded from census data, as well as rail network growth patterns recorded from maps and rail company chronologies. Such overlay comparisons are possible using conventional, noncomputer mapping techniques with acetate film, but a GIS greatly facilitates coordination of display scales and selective display of different components for easy comparison. Another use would be to compare an urban plan with mapped data on conditions in existence at the time the plan was made, then at various times after it was implemented.

Research on spatial history using GIS can take a variety of approaches. Some researchers may be interested in a specific set of questions and hypotheses, so they may need to map and evaluate only certain types of historical spatial features (e.g., county boundaries and census data). Other researchers may be more interested in developing a...