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Mapping voting blocs

What population genetics can tell us about elections

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The analogy to genetics

Population geneticists describe each person’s genome as a mixture of ancestral populations. I describe each precinct’s votes as a mixture of voting blocs. Paper (PSRM 2026) · arXiv

Map of Maine in which each town is divided into colored slices showing its mix of seven communities.

Maine towns as mixtures of seven communities: each town is filled with the share of its blocks assigned to each community, averaged over the last 1,000 saved MCMC draws.

What’s remarkable

  • Neither left nor right. The blocs don’t line up along a single partisan axis.
  • Spatial. Nothing in the model knows about geography, yet the blocs come out as contiguous regions.
  • Consistent across elections. The same blocs recur election after election. Are they political cultures?

What to do with it

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