Dealing with Shifting County Boundaries

The state of New York in 1785. Modern county boundaries are under-laid in white.

As anyone who has ever delved very deep into American research knows, the shifting boundaries of counties and even states can complicate research. You want to get right to the source, to know where to look for records of your ancestor, since many key American record types are often kept at the county level – civil vitals, probate, and deeds, to name a few. But what happens when it’s not your family member that did the moving, but the county line? This was extremely common in the earlier days of the United States as it experienced rapid growth and constant reorganization.

The state of New York is a prime example. By 1785, less than ten years after Independence, almost all of New York was in Montgomery County. By the turn of the century only fifteen years later, it had split into over ten new counties and would only continue to fracture further over the next century. A man could have been living in Montgomery County in 1785, Chenango County in 1800, and Madison County in 1815 – and all without having moved ten feet over that thirty-year span.

Another example from my own tree: my great-grandmother who just died this year at the age of 107 was born in 1906 in what is today the city of Erick in Beckham County, Oklahoma. The problem? The day she was born, neither the county nor state existed. It was then known as Indian Territory and didn’t become a state until the next year, when Beckham County was also created. It has taken some explaining to clarify why I can say she was born in Erick, Greer County, Indian Territory and my family can say Erick, Beckham, Oklahoma, and we can both be technically talking about the exact same place!

How could you possibly keep all of this straight? One great (and free!) tool to help with the shifting lines is available online through the famous Newberry Library of Chicago. Called the Atlas of Historical County Boundaries, this super-visual site allows you choose a state, then choose a year and it will generate a map of what the boundaries looked like that exact year. You can even overlay the modern county boundaries and names, check out the bibliography that led to its creation, or view chronologies for each individual county.

Although admittedly it is not the most immediately user-friendly tool out there, a little experimentation will bring you up to speed in no time. Access it online here. Start by clicking on the state of interest. From there, select method you’d prefer – to get the visual, simply click “View Interactive Map.”

If you’re from the U.S., give it a try to find yourself learning even more about the history of the United States and how it affected your family!

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Katy - Legacy Tree Genealogists Project Manager

Earning a bachelor's degree in Family History & Genealogy, along with a natural love of writing, prepared Katy to research and edit with enthusiasm. She loves history, solving mysteries, and helping others discover their heritage. Her expertise is primarily in United States genealogy but she loves exploring family history worldwide and particularly enjoys the variety that being a project manager brings.

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