This story is excerpted from the MT Lowdown, a weekly newsletter digest that showcases a more personal side of Montana Free Press’ reporting.


There’s a theory I hear often while reporting stories on Montana’s population growth: That many of the new arrivals flooding into the state are making their relocation decisions based on political identity — conservative arrivals flocking to reliably red areas where they can find neighbors with shared values, and liberals gravitating to the state’s blue urban cores.

So while looking at political data for a work-in-progress story on the state’s ongoing legislative redistricting process, I thought I’d throw together a quick chart aimed at testing that notion by evaluating whether Montana’s most partisan state House districts have in fact boomed with new arrivals over the past decade.

The answer? No, not really.

Since my editor is fond of telling me that scatterplots like this one can be confusing to anyone who doesn’t spend a bunch of time looking at data visualizations, let me explain what’s going on here: Each of the dots represents one of Montana’s 100 state House districts, the ones we use to elect legislators to the Montana House of Representatives.

Each district’s placement on the vertical axis represents how much each district grew on a percentage basis between the 2010 and 2020 censuses. For example, the light blue dot at the top of the chart, House District 65, represents the slice of northwest Bozeman that added 7,990 people over that decade, a growth rate of 81%. Most other districts, clustered lower on the chart, saw comparatively modest growth of 20% or less.

Each district’s placement left to right, as well as its color, represents how its voters have tended to vote in recent statewide elections. To calculate that partisan lean score, I’ve averaged the results from the 10 races the state redistricting commission is using to decide whether new districts it’s debating count as “competitive.” Districts toward the left side of this chart
(the bluer ones) have leaned more Democratic, while districts toward the right (colored redder) have leaned more Republican.

As it turns out though, neither the bluest nor the reddest districts saw the greatest population growth over the last decade. Instead, much of the state’s growth happened in comparatively moderate suburban districts on the outskirts of Bozeman, Missoula and Billings.

Some caveats: Firstly, the population shifts captured here, representing the decade ending in April 2020, mostly represent trends that existed before the COVID-19 pandemic. Since part of the migration theory I hear is about many new arrivals being people who wanted to escape states that maintained stricter public health restrictions, that’s an important piece of the puzzle that’s missing here.

Secondly, this data doesn’t do anything to answer one of the biggest questions about the state’s population growth: how new arrivals are changing Montana’s politics. The partisan lean number plotted here is a snapshot stat reflecting a relatively small number of races between 2016 and 2020. As such, it unfortunately doesn’t provide any insight about whether these districts are becoming redder, bluer or purpler as a result of their growth.

Even so, I do think this provides a useful data point for anyone trying to wrap their head around what growth means for Montana’s political culture. (Also, I should thank the folks who weighed in after I shared an earlier version of this graphic on Twitter last week — those comments and questions very much helped me hone my thinking here.)


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Eric DietrichDeputy Editor

Eric came to journalism in a roundabout way after studying engineering at Montana State University in Bozeman (credit, or blame, for his career direction rests with the campus's student newspaper, the Exponent). He has worked as a professional journalist in Montana since 2013, with stints at the Great Falls Tribune, Bozeman Daily Chronicle, and Solutions Journalism Network before joining the Montana Free Press newsroom in Helena full time in 2019.