What’s In A Center Of Population?

In the realm of demographics, the term “center of population” refers to the position on a map in which the average person within a country or region lives. I find this concept quite fascinating because it deals with factors that drive both population growth and human migration within a country. 

Technically, there are three different definitions of the center of population. This is according to Wikipedia. You’ve got the mean center, or “centroid”, which asks you to imagine a flat map of the region in which you place an equal weight for each person on the map. In this case, where does the map balance? This is the definition most commonly used, so it’s the one I’ll go with here.

Aerial view of Hartville, Missouri, United States - image taken from the NOAA government website.

The above image is of a relatively unassuming small town in southwestern Missouri. From the sky, it looks like just another Ozarks community. However, what is special about Hartville is that according to the 2020 United States census, it is the closest town to the average location of the United States population. What is more relevant to the study of population trends in the country, however, is the direction this centroid has moved over time.

From this Wikipedia page , we can see that the center of population was in Texas County, Missouri as of the 2010 census, roughly 12 miles from the 2020 centroid. On average, this centroid has traveled west by southwest at a rate of roughly 2 or 3 miles a year for the last thirty years. This isn’t all that much in the grand scheme of things, but it paints a fairly clear picture as to where Americans are moving. 

It should be noted that this is not a new trend; the centroid has generally shifted west and south throughout the country’s history, ever since the first census in 1790. The first question we should ask is this: Why are so many Americans moving away from the East Coast?

Here’s an anecdote for you all. I’m from an East Coast state, Massachusetts, where young professionals are leaving at a rapid rate - a WGBH survey earlier this year found that about a quarter of such people did not intend to remain in Greater Boston for the long term. In fact, according to Wikipedia, Massachusetts lost a net of about 160,000 people to other states between 2020 and 2024, a higher raw number than all but four other states and a higher relative rate than all but six states. 

So why is that? Well, here’s a visual of the biggest reason:

Anecdotally, there’s a lot of construction of single-family homes going on in suburban Massachusetts. During my undergraduate studies, every time I visited my childhood home, it seemed as though another dozen lots had been sold, torn down, and were to be replaced by homes that were grander than what stood there previously. In other words, it’s about housing costs - they’ve simply become too prohibitive for many of the people who might like to live here.

Now let’s talk about states that have benefited from this domestic migration. Florida and Texas top the list. It can probably be presumed that some people are moving there for the nice weather. Now, I don’t consider heat and humidity to be “nice weather”, and I actually think Boston has the best climate of any major U.S. city. But that’s just me.

And then there’s Arizona. Arizona, specifically the Greater Phoenix area or the “Valley of the Sun”, has grown at an impressive rate considering its location. Perhaps it is indeed the quintessential American city given how little the developers cared about urbanism. Despite the impending lack of water, and despite constant warnings from climate scientists that the city may be uninhabitable by century’s end, people and businesses still flock there. And the cost of living isn’t even that low anymore!

Thumbnail for Yellowstone, Season 2 taken from Rotten Tomatoes.

Another beneficiary of this domestic migration is Montana. On a per capita basis, it has the third-highest rate of net domestic migration, and as with Florida, a common political narrative is that tens of thousands of people moved there the last few years because they were fed up with COVID restrictions.

These new residents have been seen as a factor making the state’s politics redder, as the GOP completed their conquest of the state with Senator Jon Tester’s 7-point loss to Republican challenger Tim Sheehy. Fun fact: MT-SEN 2024 was the most expensive congressional election in US history relative to the number of votes cast - nearly $500 was spent for every vote.

Montana is still thinly populated. Despite its extensive land area, it only has about 1.14 million people, less than 8 per square mile. Nonetheless, this number is rapidly growing as more people are inspired by shows like Yellowstone to move to Montana and live out their cowboy fantasies. It’s a bit ironic, too, because from what I understand, Yellowstone is an allegory for how out-of-staters shouldn’t be moving to Montana and ruining it for the natives. And yet it’s contributed to the real-life gentrification of the state!

It is worth noting, of course, that the United States is not the only country with a center of population. I’m not going to engage in unnecessary “USDefaultism” here, so let’s look at this map from the CIA World Factbook:

As you can see, the point on Earth closest to the average person is in what appears to be northern Pakistan - it’s an average of about 3,000 miles to everyone else. Given how populated South Asia, and Asia in general, is, this isn’t much of a surprise. By contrast, the farthest point from each person is just off the western coast of Chile. That’s where you’d end up if you dug a hole all the way through.

So what are the takeaways from the center of population concept? Well, I think it’s a reminder that there are very real pressures driving people to move to certain parts of the world and not others. My own state’s center of population isn’t that far west of Boston (it’s in the town of Natick). This is of course not uniform - there are people who’d rather live in rural areas. They may not be a majority, but they exist. Still, over time, we should expect the urban percentage of the population to increase. 

Thank you for reading.