The latest evidence of the political influence of density.

The below graph from Conor Sen, an armchair demographer in Atlanta, has been making the rounds this morning in my Twitter feed. It neatly reflects a political phenomenon we've written about before: Yes, cities generally tend to lean more Democratic, and rural states more Republican, but the fine-grained relationship between politics and population density is actually quite remarkable.

This scatter plot looks at congressional districts, which are ranked according to the Cook Parisan Voting Index. That measure essentially reflects how Republican or Democratic a district leans (by percentage of voters, not ideological purity) relative to the national average. A Democratic district shown above as +10, for example, gave the Democratic candidate in the last two presidential elections on average 10 points more of the local vote (say, 63 percent compared to 53 percent) than the nation-wide vote.

Sen compared that data with Census data on population density by congressional district. Here is how a smarter person than me interpreted the resulting picture:


But you may also be struck by the shape of that trend line (Sen is quick to note, by the way, that he's not a statistician). It roughly suggests a political tipping point somewhere around a population density of about 800-1,000 people per square mile. That's actually a number that we've seen before. Here is a different take on the same question, looking at presidential votes by county in the 2012 election, via Dave Troy:

Troy concluded that, "at about 800 people per square mile, people switch from voting primarily Republican to voting primarily Democratic." Richard Florida looked in more depth at that finding last November with a broader conversation on what this trend really says about our differing political preferences and needs in crowded cities and leafy exurbs.

Feel free to weigh in below on why you think your politics may be tied to the proximity of your neighbors (or maybe they're not?). Sen is a bit more zen about what all of this portends for the state of the country in an email: "The big realization I had a couple years ago was if the last era (call it 1982-2007) was driven by debt, the next one (2008-??) appears to be driven by demographics, and I'm trying to get ahead of the curve."

About the Author

Most Popular

  1. A house with a for sale sign.
    Perspective

    Why Are Zoning Laws Defining What Constitutes a Family?

    It’s wrong to exclude safe uses of housing because of who belongs to a household. Like family law, zoning ordinances should prioritize functional families.

  2. a photo collage of 2020 presidential candidates.
    Equity

    Will Housing Swing the 2020 Election?

    Among Democratic candidates for president, the politics of America’s housing affordability crisis are getting complicated. Just wait until Trump barges in.

  3. a photo of Denver city council member Candi CdeBaca
    Transportation

    A Freeway Fight Launched Denver’s New Queer Latina Councilmember

    In a progressive shake-up, 32-year-old community organizer Candi CdeBaca will take her advocacy work to the city council.  

  4. A cat lays flat on a bench at a park on the outskirts of Tokyo.
    Life

    Why Don't Americans Use Their Parks at Night?

    Most cities aren’t fond of letting people use parks after dark. But there are good lifestyle, environmental, and safety reasons to reconsider.

  5. A map of apartment searches in the U.S.
    Maps

    Where America’s Renters Want to Move Next

    A new report that tracks apartment searches between U.S. cities reveals the moving aspirations of a certain set of renters.

×