05 June 2011

New and simple online tool uses Google Maps to show historical county boundaries

Thanks so much for all of the interest in this tool, and for your positive comments and constructive feedback!  I've incorporated several enhancements into the current version.

We all know the importance of county governments for maintaining various types of records that are useful for genealogical research.  But how often have you tried searching for an ancestor's historical records for a given county, only to realize that you were searching in the right place but the wrong county?  In fact, according to John H. Long, the director of the Atlas of Historical County Boundaries Project at the Newberry Library, "the average number of boundary changes per county in the U.S. is 4.5".  This means that there's a very good chance that you are sometimes looking in the wrong county for some of your historical genealogical records.

Using the fantastic information from the Atlas of Historical County Boundaries, I've created an online Historical County Boundary Maps tool based on Google Maps.  You can type in ANY PRESENT-DAY PLACE in the U.S. and ANY HISTORICAL YEAR to see the map of county boundaries then in effect, along with all of the current Google Maps places, roads, etc to put the historical map in a current and familiar context!  You can then click any county on the map to see the specific history of the boundary changes, and type in different years to see the boundary changes over time.  Here's how to do it:

1. Go to this page on my website:  Historical County Boundary Maps

2. Type a PRESENT-day Place and a HISTORICAL Year, then hit the "Go!" button.  The place you type MUST be a PRESENT-day city, town, or county; you can even type a current day address or road name*.  The year can be from the mid-1600s (depending on date of state formation) through the year 2000.

3. Once you see county boundaries, click inside any county to see its name and details.  The info window will list the county name and when that county's then-current boundaries (as of the date you selected) went into effect.  Type a year prior to the effective date to see the prior boundaries.

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* The Place box uses a standard Google Maps geocoding engine, therefore you can type present-day street addresses, road names, points of interest, and the like, and then type in the correct historical year to see what county that address or road was located in back then (e.g. type "Silver Oaks Cemetery, Tyner, TN" or "Old Lee Highway, Tyner, TN" together with the year 1880).  Of course, this doesn't account for addresses or road names that may have changed, so if you suspect that, then just start with the right present-day town or city name.
- This tool works best with Chrome, Safari (including iPad), and many other browsers.  There are known issues with some versions of Internet Explorer.  For some mobile browsers, click the "View web version" link at the bottom of this page on the mobile browser.
- Occasionally, county lines may take up to 10 seconds to appear; if the county lines never appear, try refreshing the page (F5) and try your search again.
- This tool uses an experimental Google Maps API feature called Fusion Table Layers.  The underlying county boundary map files used are quite large, and Google Fusion Tables are themselves a beta product.  As with any new and innovative technology, don't be surprised if things occasionally don't function as expected.
- Currently, county boundaries must be viewed one state at a time.

- The fantastic source of the historical county boundaries and related information used in this tool is the Atlas of Historical County Boundaries, a project of The Dr. William M. Scholl Center for American History and Culture at The Newberry Library in Chicago, Illinois.  The information is included in my website under the creative commons license shown on the bottom of the linked page.

I hope you find this tool useful in your research!  I plan to continue to enhance the tool and add functionality, so feel free to leave comments below on what you like, and what you'd like to see improved or added to future versions.