Historical U.S. County Boundary Maps

Show complete county change chronology for the red map marker location thru date above
randymajors.com Historical U.S. County Boundary Maps tool, v 3.57 ©2019 Randy Majors, except:
county data are from the Atlas of Historical County Boundaries, included in this tool under the Creative Commons license shown in footer here.
This free tool lets you view Google Maps with historical county boundary lines. Why is this useful? Because county boundaries change over time. With this tool built on Google Maps, you can make sure you're looking in the right county for the place and historical years you're researching.


1. Type a PRESENT-day Place and a HISTORICAL Year or Date, then click the "Go!" button. The place you type must be a PRESENT-day U.S. city, county, place or address. You can enter a 4-digit year or a date in the format M/D/YYYY. The date can be from the mid-1600s (depending on date of state formation) through 12/31/2000.
Historical county boundaries will draw, and an information pane about the county of interest will appear at the bottom of the map. The information pane lists the historical county name at the red marker, and provides details on the latest boundary change as of the date you typed, including reference to the particular statute that triggered the change.

2. Google Maps with ZIP Codes NEW! Click the "Use current location" button to the right of the "Go!" button to determine what county your current location was part of as of the date or year you specified, and to see all of the historical county boundaries near you.
3. Historical County Boundaries Click the "Toggle fullscreen view" button in the upper right of the map for a much larger map and an immersive full screen experience. (Not available on iOS)
4. Explore the map! Click the < and > buttons next to the Year input box to go back and forward a decade at a time (or type any particular historical date). Zoom in for more detail, pan to another state or change to satellite view. When you're ready to learn about another place, you can either type it in the box or click the map to get information on another location.
5. See places on the map where you can research more about your area of interest by choosing an option from the "Show Research Locations" drop-down menu at the bottom of the map, including places such as courthouses, cemeteries, churches, and libraries. Click the icons that appear for more information and links to that place. See this post for more information on this functionality.
6. NEW: See full county chronology of your selected location with one click! Just check the "Show complete county change chronology for the red map marker location thru date above" checkbox below the map. You can also set the update interval that controls how quickly the map and list changes as you go back in time. See this post for more information on this functionality.
7. Share this tool using the social sharing buttons at the bottom of the page. Subscribe to this blog at right to stay abreast of updates and tips.

Looking for present-day county boundaries on Google Maps? Here it is: County Lines on Google Maps.

- 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 an historical year to see what county that address or road was located in back then. 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.
- The "Use current location" button will be more accurate on smartphones and other devices containing a GPS; desktop browsers typically show an approximate location.
- The information lists the full place name in the form of "Place, Historical County, State, USA". To save time, you can highlight this text and Copy (Ctrl+C) and Paste (Ctrl+V) it into your genealogy program's location field.
- 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.
- County boundaries must be viewed one state at a time due to states having overlapping claims for the same area in some historical years. To aid in multi-state searches, when you drag the map such that it's center falls in another state, you will be asked if you wish to show county boundaries for that new state instead.

- 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 this tool under the Creative Commons license shown on the bottom of the linked page.

Help improve this tool. Please comment here.

Also, check out the AncestorSearch using Google Custom Search tool on this website to build a Google search that is optimized to find web pages mentioning your ancestors! The search returns a more focused set of results by using advanced Google search techniques including exact phrases, forward and reverse name order, alternate name spellings, logical operators, and so on.