The economies of modern cities are dependent on an advanced retail system; so too are the people who inhabit them. The origin and evolution of retailing in London, Canada, was studied using a historical geographic information system (GIS) to document the relationship between a city and its retail sector. Visualization and spatial-statistical techniques afforded by the historical GIS were implemented to study change over time. The locations of retailers and the types of the goods they sold were examined for four periods in the city’s early history: 1844, 1863, 1881, and 1916. The distances traveled to shop were also calculated for a variety of goods. The results indicate that the retail system was ingrained in the development of the city, showing marked locational patterns and a high degree of rationality in the shopkeepers' business strategies. Mapping the retail landscape in each era using historical GIS allowed for the examination of the relationship between retail and residential development in the growing city. While the downtown area remained the primary retail district for the city, considerable retail expansion also occurred at the urban periphery during this early stage of the city's development.

Over the past decade or so geographic information systems (GIS) methodology has become an accepted tool in historical research (Gregory and Ell 2007; Knowles 2008). Although often regarded as a mapping tool, GIS is perhaps better thought of as a type of database. What makes a GIS database unique is that a location is stored for each item of data, with this location taking any of a variety of forms: a point, a line, a polygon representing an area or zone, or, in the case of a raster system, a pixel. GIS can then present instantly on the screen a map showing the distribution of any variable or combination of variables in any of the chosen locational formats. This electronic display of information becomes an analytic tool, allowing the refinement of research questions, with answers displayed instantly: GIS creates a display of information once visible only in paper form, drawn slowly and expensively first by cartographers and then by vector plotters. GIS and its associated tools transform mapping into a dynamic exploratory process.

Montreal in 1881 was highly segregated along four distinct social dimensions: language, religion, socioeconomic status, and sector of employment. By 1901 the population had doubled, and we examine changes in residential distributions over the two decades. Despite the increased integration of certain groups, segregation remains high, and multiple dimensions are still discernible. In addition to long-established communities of French Canadians, Irish Catholics, and Anglo-Protestants, we see new streams of immigrants occupying their own patches in the urban fabric. To make meaningful observations of sociospatial changes over two decades, we used a geographic information system (GIS) to situate individual census households with spatial precision on 1 of 12,000 lots in 1881 and 30,000 in 1901, so that we could reaggregate them into meaningful districts of different scales and districts with identical boundaries for both years of observation, thereby overcoming the major methodological problems hindering previous comparative analyses. Coupling well-established statistical indexes of segregation and diversity in a GIS framework lends new analytic power to grasp the scale of phenomena and inquire into behavioral choices of nineteenth-century households. The empirical evidence shows how both concentration and diversity were built into the urban fabric. This study also offers methodological cues for comparative studies in other places and periods.

The unique feature of geographic information systems (GIS) and other forms of historical data visualization is the capacity to hold and display large amounts of data associated with spatial reference points. This software can display all data for a given point, a single variable for all points, or, most important, any combination of variables across all reference points. In doing so, these systems bring to the screen instantly and cheaply a display of information once visible only in paper form, drawn slowly and expensively, first by cartographers and then by vector plotters. This project deploys GIS to help us understand the intersection of social and political life in nineteenth-century Alexandria, Virginia, and Newport, Kentucky—medium-sized cities with populations under 20,000. Commercial Alexandria, with a race-based labor system, and industrial Newport, with an immigrant labor system, present an analytically useful mix of commonalities and differences.

Creating a historical narrative for a place has traditionally entailed consulting the source materials that have managed to survive over time, interpreting those records, and constructing a narrative for how that place came to be. Until recently historians have often viewed technology and its ability to contribute to this process with skepticism if not outright hostility. Contrary to this view, geographic information systems (GIS) can add to, and not detract from, the creation of a historical narrative for a specific place. Apart from the Great Fire of Seattle in 1889, the regrading and removal of Denny Hill (1898–1930) arguably represents the most iconic period in Seattle’s urban history. The Denny Regrade, the removal of a 245-foot hill that once buttressed Seattle’s downtown retail and commercial districts, remains prominent in the historical consciousness of Seattle, as it represents a period of intense and dramatic change. GIS, and in particular historical GIS, offers the opportunity to more deeply explore and re-create the history of the Denny Regrade due to its inherent ability to spatially integrate, visualize, and analyze information. Using the Denny Regrade as a case study, this article examines the application of historical GIS to a topic in urban history across an extended temporal scale (1893–2008). Three main areas are discussed. The historical context of the Denny Regrade is explored; components of the historical GIS developed for the study are examined; and examples of geovisualizations and new historical data and information are presented.