Crime mapping has long been an integral part of the process known today as crime analysis. The New York City Police Department, for example, has traced the use of maps back to at least 1900. The traditional crime map was a jumbo representation of a jurisdiction with pins stuck in it (figure 1.1). The old pin maps were useful for showing where crimes occurred, but they had serious limitations. As they were updated, the prior crime patterns were lost. While raw data could be archived, maps could not, except perhaps by photographing them.1 The maps were static; they could not be manipulated or queried. For example, it would have been difficult to track a series of robberies that might overlap the duration (a week or month) of a pin map. Also, pin maps could be quite difficult to read when several types of crime, usually represented by pins of different colors, were mixed together. Pin maps occupied considerable wall space; Canter (1997) noted that to make a single wall map of the 610 square miles of Baltimore County, 12 maps had to be joined, covering 70 square feet. Thus pin maps had limited value—they could be used effectively but only for a short time. However, pin maps are sometimes still used today because their large scales allow patterns to be seen over an entire jurisdiction in detail.
The manual approach of pin mapping gave way during the past decade or so to computer mapping-specifically, desktop computer mapping. For decades before desktop computer mapping, the process was carried out on gigantic mainframe computers using an extremely labor—intensive process. First, much labor was involved in describing the boundaries of the map with numbered coordinates on punched cards. Then came the labor of keypunching the cards, followed by a similar process of coding and keypunching to put the data on the map.
In summary, these maps:
- Are pictures of information about areas and places.
- Help us visualize data.
- Are like the proverbial pictures worth a thousand words.
- Enable information to be seen at a glance.
Hope this information helped.
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