The Washington PostDemocracy Dies in Darkness

Congress is getting more polarized — but so is your own state legislature

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We all tend to conflate "polarization" -- how far apart two groups of people are -- with "partisanship," which is a scale of loyalty to a party. And we do this, in part, because they overlap. New data from the Measuring American Legislatures project run by Georgetown University professor Boris Shor and Princeton University's Nolan McCarty, though, includes a look at how polarized each state's legislature is -- and shows why polarization and partisanship aren't the same.

We've seen similar data at the federal level before; as you may recall, congressional polarization is at an all-time high. At the state level, legislatures vary widely.


The most polarized state legislature in the country is California's, followed by Colorado and Arizona. And those three are pretty far ahead of the pack (with California in front by several lengths). (Curious what the numbers actually mean? You can read more here, but, in short, the researchers assigned a numeric value to the partisanship of each legislative chamber, and this value is the difference between those two.)

At the other end are the least polarized chambers, with Rhode Island at the very bottom -- i.e. least polarized. The state's Republicans tend to be fairly moderate, which means less distance from their Democratic opponents.

But, again, more partisanship doesn't necessarily mean more polarization. According to the researchers, New York has the most liberal and Oklahoma the most conservative legislatures. Since polarization measures the distance between the parties, you can see how more extreme legislatures might be less polarized. (Although California is still the third-most liberal.)

Change since 1997

It's also interesting to consider how this has changed. The oldest data set with the most data per state (you'll notice gaps in the data) is from 1997. We compared polarization data between now and 17 years ago. A few states have become less polarized -- South Dakota, New Hampshire, Alaska and Wyoming. Every other state's legislature has grown more polarized over time, and none moreso than Colorado's.

What does this mean for people in these states? It depends. The Democratic majority in California probably doesn't mind its polarized legislature, nor does Oklahoma probably mind that it has the most conservative legislature. It's when polarization leads to futility and obstructionism that it becomes a problem.

Yes, we're talking about you, Congress.