When you work with people at the county level as much as we do, one of the first things you notice is that there’s a big lot of counties in different states that have similar-sounding names. In fact, you get a fun reminder that there’s a really big lot of counties in the U.S. that have the same name.

One day, I started wondering:

What are the most common county names in the United States?

In other words, what county names are repeated the most times across different states?

Well, if you think about it for a second, you can probably make a few good guesses by just pulling from a list of the nation’s founders. The most common, as you might have bet correctly, is Washington, at 31. As a matter of fact, there are 30 Washington Counties across the U.S. and a Washington Parish in Louisiana.

I got curious about this one day, had some spare time, and looked it up. Wikipedia has a fun article that served as the basis of my “research,” on this question (pressing issue, I know), and much to my delight, it documents well beyond the top five or ten most common county names. In fact, it includes pretty much every name of a county or county-equivalent (including districts, parishes, independent cities, and others) that’s repeated more than once somewhere in the U.S.

It also includes this cool map.

 

Here, you can see the top five most common county names plotted out on a national map: Washington (31), Jefferson (26), Franklin (25), Jackson (24), and Lincoln (also 24). If you want to roll Jackson and Lincoln together since they’re tied, the next most common county name is Madison at 20 (not pictured).

 

Then I got curious, and thought:

“Well, what are the next top five?”

And then, a little more curious:

“…And where are they?”

See, while the article lists what the rest of the common county names are, it didn’t list where they were.

So, I called on one of my best friends: the list of all U.S. counties’ FIPS codes with their corresponding names.

Soon enough, I had lined up nearly every state in a line of columns populated with the name of every county within each state. The data was all there. I just had to figure out what to do with it.

I was also able to use a wonderful online tool that I highly recommend: the USA Counties Map by MapChart. I was able to use it to manually put together a map of the “next,” top five most common county names.

But even that doesn’t paint the full picture. As you can see in the map’s legend, Clay, Montgomery, and Union, are actually all tied for their rank with 18 states having a county with those names.

But at the start of this, I had one question at the top of my mind:

What two states have the greatest number of same-name counties?

This is to say, which two states have the most overlap or commonalities in the names of their respective counties?

With a bit of scanning, guessing, and reasoning, I narrowed down a small handful of pairs of states that I thought might have a particularly noticeable amount of overlap.

If my math is right, it would seem that the two states which have the highest order of shared county names are Illinois and Indiana, which makes sense! They’re right next to each other, they were both admitted to the Union just two years apart (Indiana in 1816 and Illinois in 1818), and they share a strong amount of historical connection to the broader Great Lakes Region.

The Prairie and the Hoosier States have a total of 43 counties with the same name out of 102 total in Illinois and 92 total in Indiana. This means that if you randomly picked a county in Illinois, you’d have roughly a 42.16 percent chance of picking a county which exists under the same name in Indiana. Conversely, if you randomly picked a county in Indiana, you’d have an even greater, roughly 46.74 percent chance of picking a county with the same name in Illinois.

And then I got to thinking, “I wonder if you could test that for every possible combination of states in the country…”

…It was at this moment that I realized I was a bit in-over-my-head in regards to the statistical legwork that would be required to pull this off, namely a hearty degree of pairwise testing.

More bluntly, that’s a question that will take a lot of math to answer.

To me, there’s something beautiful about the commonality of a place’s name. One might be inclined to think that this could be a knock against the uniqueness of their county when they come to find that several dozen other counties across the country have the same name. But I find it to be quite the opposite. As someone who lives in a county whose name is repeated eight times across the nation, I for one find myself all the more curious about the ways in which all the other Fulton Counties are distinct in their own identities.

In fact, I realized that there are so many questions you could ask with this kind of information that I thought I’d try and start writing a little bit of a “series,” on the random bits of trivia I came across. Once I had compiled all the names in one place, I really started to have fun with running different pair-based tests. It almost felt like playing a game, so much so that I thought I’d call this the Same-Name County Game. How do you play? I’m not sure yet. But stay tuned, and maybe we can find out together.