Navigating Shifting Boundaries

Have you ever had difficulty locating the name of an ancestor’s county of birth? Perhaps you have noticed an ancestor’s county of residence is not the same as today? This is not uncommon, as county boundaries changed a lot in the early days of each state, particularly as it became more settled and populated. In fact, some counties have morphed in recent years as well. All of these changes can be quite confusing as a result, but do not fret!

Thankfully, there is a free online resource that makes these changes easier to track with interactive maps, indexes, and chronologies. The Atlas of Historical County Boundaries from the Newberry Library is an amazing project that you may find very helpful for your genealogical research. More specifically, “The Atlas presents in maps and text complete data about the creation and all subsequent changes (dated to the day) in the size, shape, and location of every county in the fifty United States and the District of Columbia.” To learn more, watch a brief introductory video about these changes.

Organized by state and then county, this extremely detailed resource aims to be comprehensive, covering changes from the inception of each colony/state, from the early 1600s to the year 2000. (You can move through each change by selecting the dates from the menu on each state’s interactive map page.) According to the information on the About the Project page, “The principal sources for these data are the most authoritative available: the session laws of the colonies, territories, and states that created and changed the counties.” In other words, you can trust the information on this site, as they have done extensive research and consulted the most reliable and authoritative sources. You can even view their sources on each state page as well as the publications that have been informed by this data.

To learn more about this valuable resource, check out the Using the Atlas page. This section will guide you through how to use the various tools and make the most of the information that is available on the site. For example, you can print and download the information that you find so that it is easier to locate later. You can also use resources like Google Earth to further manipulate and customize the maps for your ancestral locales. For more about this option, check out the Download Files page for step-by-step instructions.

If you want to hear about other ways this resource can be used, check out this Family Tree Magazine podcast episode. Kenneth Marks also recently featured it as a valuable free website for genealogical research. As you can see, many people have found this resource to be very helpful, and perhaps you will as well! Give it a try and see if it helps clear up some confusion or break through a brick wall (or two!).

Bonus Trivia: Did you know that Lake County, Illinois, was created on March 1, 1839, from McHenry County, and its boundaries have remained fixed since then?