1 Non-boundary Jurisdictional Data in Historical GIS: Examples from the Atlas of Historical County Boundaries A Presentation to the International Workshop on Historical GIS

designed to compile, map, and disseminate all changes in the jurisdiction of every county in the United States of America, from the early 1600s to the present. As the name of the project implies, we spend most of our time working on alterations in boundary lines, but our interest extends beyond boundaries to include extinct counties, unsuccessful proposals for new counties, changes in state boundaries and their effect on counties, non-county areas, organization of county governments, and attachments of unorganized counties and non-county areas to fully operational counties. Even though they can be important and interesting in their own right, boundary changes seldom are the direct object of a researcher’s inquiry. Nevertheless, they can exert a powerful influence. Most often they interfere with the analysis of historical statistics, like census returns, or a search for such essential records as certificates of births and deaths. We convert those obstacles into aids by collecting all the relevant information and presenting it in useful and authoritative ways. Our goal is to produce a long-lasting resource for future research. In the United States there have been thousands of jurisdictional changes at the state and county levels. In the United States today there are about 3,100 counties or equivalents, and each one has changed approximately 5 times. Most changes occurred before the twentieth century. The stat