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The National Historical Geographic Information System (NHGIS) is a new project to make a rich body of aggregate census data accessible within a Geographic Information Systems (GIS) framework for historical population research. The authors are developing a database incorporating all available aggregate census information for the United States between 1790 and 2000, including all surviving machine-readable aggregate data and new data transcribed from printed and manuscript sources. They are also creating new census-tract maps back to 1910, state and county maps back to 1790, and additional maps when feasible. Availability of high-quality boundaries for key statistical areas will permit the reconciliation of changes in census geography. Census data, documentation, and boundary files will be freely disseminated through an integrated Web-based data access and mapping system.
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Fitch et al. (2003) studied this question.
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