Online U.S. Atlas of Historical County Boundaries

One of the more useful tools for genealogists is the Atlas of Historical County Boundaries created by the Newberry Library in Chicago. When I first started in genealogy, one of my biggest frustrations was trying to find records of ancestors in the county where they lived. Many genealogical records are created by counties. In many cases, I knew the town where they lived and I also knew what county the town was in. Yet I couldn’t find the records that normally are kept in county courthouses, such as probate records or the deeds of land transfers.

As I gained more experience, I soon learned that the problem was mine. I had looked in the country records for the county lines of today. In many cases, the county lines had moved over the years, even though my ancestors had not moved an inch. Once recorded at the county courthouse, records normally remain at that courthouse forever, even if the county lines are redrawn later and the property or the town in question is then “moved” to a different county.

For instance, if your ancestor lived in the town of Smallville in Washington County when the information was recorded at the courthouse and later the county lines were redrawn so that town of Smallville and your ancestor’s location were later in Lincoln County, you still need to look for older records in the Washington County courthouse. Existing courthouse records usually are not moved to a new courthouse when county lines are redrawn.

Experienced genealogists all know that you need to look in the county courthouse for the correct county as of the date the records were filed. But how do you find the the correct county lines as of the date(s) your ancestors lived there and left records? You can find several books at well-equipped libraries that will provide that information. However, the Atlas of Historical County Boundaries will provide the information as well without requiring the time and travel expenses of visiting a well-equipped library. Yes, you can find the information without leaving home. The Atlas of Historical County Boundaries web site is available FREE of charge. You can even download the files to your own computer and save them or use them as you please. The online atlas has been available for years but I find that many genealogists are unaware of its existence and do not know how useful it can be.

With the Atlas of Historical County Boundaries, you can view records on a per state basis, an interactive map, or choose the time slots that best meet your requirements. You can search by location or by time or by both. To use the web site for the first time, select a state from the map on the site’s home page to view all of the Atlas’ content related to that state, including shapefiles, chronologies, and metadata. If you cannot quickly find the information you seek, narrow the search by choosing from the available list of options. Probably the most useful option for genealogists is to display maps by dates.

A lot of helpful information about the site can be found on the “Using the Atlas” page at:

This is a web site worth bookmarking. You probably won’t need to use it often but, if you do ever have a need, it can supply the information you seek quickly.

The Atlas of Historical County Boundaries is available at the Newberry Library’s web site at:


Plus, the index to the counties includes the citation for the statute that created the county. Very helpful!


Your readers may also find this free tool I built based on the excellent Newberry source in your article:
Simply type a PRESENT-DAY address, city or place, then type any HISTORICAL date, and the historical county boundaries from that date will appear overlaid on a familiar Google Map (including satellite view). Then optionally overlay research locations on the map such as courthouses, cemeteries, churches, and libraries, and link right to them for more information. It also displays the statute that formed the boundary, and optionally animate the change in boundaries over time for that location. Over 60,000 visits to this tool I think largely due to its simple usability.

Liked by 2 people

    This is a good tool, but it too doesn’t give historical county names for Indian Territory. I typed my town, Durant, Oklahoma, and used 1880 as the year. All it gave me was “Indian Territory” for the county name. At that time, the full place name would have been Durant, Blue County, Choctaw Nation, Indian Territory. Also it was the Treaty of Dancing Rabbit Creek, signed September 27,1830, that gave lands west of Arkansas to the Choctaw Tribe to replace the lands they gave up in the Eastern part of the United States.


    I cannot say with authority, but I understand that these books – and now online databases – are based on meticulous searches of state and county records. Did the state and county have records of Indian Territory? Perhaps the tribal land information has not been accessed. Possibly bringing this to their attention would add to the database.


Another problem is when the location names were changed.


It’s good to have this information on the web for all the states and accessible on line.. Years ago, I found a published book for my state of this series in my state archives. I promptly purchased a copy for my personal use, which I use frequently.


Too bad it only shows Oklahoma Territory counties until statehood in 1907. Would be a valuable resource to include the Indian Territory counties before statehood also.


We’ve been using the atlas since it started (have real PRINT copies of some of the books!) and have found it to be exactly what we needed to find those “lost” ancestors who never moved but lived in three different counties!! So glad to see it online and using something like the format of the Animap software to take you through the changes.


    Animap is worth the investment to buy the program. i had trouble finding my paternal gr grandmother cemetery in Salem, MO. The Gen Soc was not helpful and she was not found in Salem, Dent Co., MO. It was Texas CO as boundaries had changed. Thanks Animap.


Can’t reply to Carolyn’s reply to my comment so will reply this way. Payne County of today was not part of Indian Territory. Indian Territory was the tribal lands of the Five Civilized Tribes in what is mostly eastern Oklahoma today. Indian Territory was not made up of reservations. It was Indian land owned by the tribes. There is a difference. Where are these maps that show the changes from Indian Territory counties to Oklahoma state counties?


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