The online Atlas of Historical County Boundaries is a go-to resource for determining old U.S. county boundaries.
How to find county boundaries with the Atlas of Historical County Boundaries in three steps
1. From the Atlas home page, click on the state of interest from the national interactive map.
2. From the state page, click on View Index of Counties and Equivalents. This will show you all current and past county names.
3. From this page, click on your targeted county. You’ll find a timeline of that county’s boundary changes.
Use the timeline to discover what county your ancestors belonged to at any given time. Perhaps you’ll discover you should actually be looking for an ancestor’s marriage record or probate in a parent county, one that existed there before the current county, or in a successor county later carved out of this one.
Google Earth Bonus: The Atlas of Historical Boundary Changes state pages include downloadable maps compatible with Google Earth and Google Maps. If you are not using Google Earth for genealogy yet, watch Lisa Louise Cooke’s free video to see how and why you want to use this amazing 3D map of the world for your family history! You can learn more about downloading the Atlas of Historical County Boundaries files to Google Earth in Lisa’s book The Genealogist’s Google Toolbox.
Learn More about Using Interactive Maps for Genealogy
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- Historical Maps of New York City and More Now Free Online
- Family Maps and Migration Routes Traced with New Tech Tools