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One-stop shopping for county line history

So last week The Legal Genealogist revisited the issue of county lines… and how some counties were formed, but not actually organized for governmental purposes for a while, so their records were kept by another county to which they were “attached” until they got up and running.1

Which prompted reader Doris Waggoner to note that she’d once been given a website for finding county formation in one state, but looking at that site, didn’t find all states and a list of when all counties in each state were formed, let alone organized. So, she asked, “Do you have a website for those?”


Sure do.

It’s part of the Atlas of Historical County Boundaries from the Dr. William M. Scholl Center for American History and Culture at The Newberry Library in Chicago, and for the creation of counties and changes in county line boundaries, it’s just about the best thing since sliced bread.

Newberry atlasThe Atlas of Historical County Boundaries is one of the easiest, most complete, sites to track county boundaries. As the site says, it has “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. It also includes non-county areas, unsuccessful authorizations for new counties, changes in county names and organization, and the temporary attachments of non-county areas and unorganized counties to fully functioning counties.”2

And the Atlas is “designed to be as comprehensive as possible, leaving no gaps in either space or time. The historical scope covers every day, starting in the early 1600s and extending through the end of the year 2000. Geographically, the range for each state includes all the territory within its bounds in 2000, regardless of what government created or altered a county there, plus any other territory that may have been within the state’s jurisdiction at an earlier time.”3

You can “(s)elect a state from the map to view all of the Atlas’ content related to that state, including shapefiles, chronologies, and metadata”4 and then “(c)hoose a date (day, month, and year) to view historical county configurations against the modern county network. Use the toolbar to zoom, pan, measure, view descriptions and citations, or print a desired map.”5

Now … it may seem like a bit of a pain to have to mouse over a map and click on a county to get the historical data.

But the fact is… you don’t have to. There are also state-by-state, county-by-county descriptions in a much easier-to-access form.

Using South Dakota as an example, since as the blog post noted that was the state with the very last unorganized counties in the country,6 here’s how you get to this amazing wealth of information:

From the main page of the Atlas of Historical County Boundaries, click on the map for the state you’re interested in, such as South Dakota.

From the page that then appears for South Dakota, there are a number of links to reference materials including the Index of Counties and Equivalents, the Consolidated Chronology of State and County Boundaries, and the Individual County Chronologies.

• The Index of Counties and Equivalents provides a “complete index of every county, county equivalent, or other area relevant to the evolution of state and county boundaries; includes extinct and proposed counties, non-county areas, and provides cross references for name changes, and hyperlinks to corresponding entries from the Individual County Chronologies.”7 So, for example, clicking this brings up a list that begins with “ADAMS (Dakota Territory, proposed)” and proceeds through “ZIEBACH (S.D., original, extinct)” and “ZIEBACH (S.D.).” I can click on an individual county or place and go directly to its complete history.

• The Consolidated Chronology of State and County Boundaries “organizes the historical data chronologically, combining all the county events into a single composite entry for each date. Each entry is followed by a citation to the primary source(s) used to determine the change.”8 And that one returns an error message for South Dakota — but the data is there: it’s with North Dakota and the Dakota Territory and accessible at the Individual County Chronologies link.

• The Individual County Chronologies is a section that “organizes the historical data alphabetically by county name with each entry covering all the changes to a single county or equivalent. Each entry is followed by a citation to the primary source(s) used to determine the change.”9 And clicking on that one brings up an alphabetical list of every proposed, extinct and current county anywhere in the Dakotas.

The best part? The exact legal reference to the county formation or change is cited right with the entry. So, for example, with Dewey County, where my great uncle John lived, the first entry tells me that on 8 January 1873, Rusk County (now Dewey County) was created by Dakota Territory in present South Dakota from Non-County Area. Rusk was not fully organized, and not attached to another county. And it cites: “Dak. Terr. Laws 1872, 10th sess., ch. 19, sec. 7/p. 46.”10

One-stop shopping for county line history.

It doesn’t get any better than this.


  1. Judy G. Russell, “Reprise: Organizing the counties,” The Legal Genealogist, posted 2 Feb 2018 ( : accessed 5 Feb 2018).
  2. “What is the Atlas?,” About the Project, Atlas of Historical County Boundaries, The Newberry Library ( : accessed 5 Feb 2018).
  3. Ibid., “Scope.”
  4. State Data,” Atlas of Historical County Boundaries, Newberry Library ( : accessed 5 Feb 2018).
  5. Ibid., entry for South Dakota.
  6. See Russell, “Reprise: Organizing the counties.”
  7. South Dakota, Atlas of Historical County Boundaries.
  8. Ibid.
  9. Ibid.
  10. “DEWEY (S.D., created as RUSK),” Dakota Territory, South Dakota, and North Dakota: Individual County Chronologies, Atlas of Historical County Boundaries.
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